The preposition is an invariable part of the sentence that establishes a relation between two words. They don't have a meaning of their own and show position, time, relationship, etc. between words.  Some of the uses of prepositions are shown below:
preposition + infinitive [more]
 Ella sigue sin mirar atrás.
 Ella sigue sin mirar atrás.
She keeps going without looking back.
 Él salió sin decir adiós.
 Él salió sin decir adiós.
He left without saying goodbye.
 Yo tengo un boleto para viajar.
 Yo tengo un boleto para viajar.
I have a ticket to travel. 
preposition + pronoun [more]
 Para ti lo hace.
 Para ti lo hace.
For you, he does it.
 Gracias, hoy por ti, mañana por mí.
 Gracias, hoy por ti, mañana por mí.
Thank you, today for you tomorrow for me.
 Ellos compartieron la herencia entre todos.
 Ellos compartieron la herencia entre todos.
They shared the inheritance among themselves.
preposition + noun [more]
note: sometimes the noun is also modified by an article or an adjective.
 Yo prefiero el bocadillo sin queso.
 Yo prefiero el bocadillo sin queso.
I prefer the sandwich without cheese.
 Tenía los codos sobre la mesa.
 Tenía los codos sobre la mesa.
He had his elbows on the table.
 Él estaba cantando bajo la lluvia.
 Él estaba cantando bajo la lluvia.
He was singing under the rain.
verb + preposition [more]
 Soy de Guatemala.
 Soy de Guatemala.
I'm from Guatemala.
 Trabajo con los caballos.
 Trabajo con los caballos.
I work with horses.
 Corrimos hacia su casa.
 Corrimos hacia su casa.
We ran to his/her house.
 
Prepositions are words that help us establish relations between different elements of a sentence. They can show a movement, time, position, and relationship among two or more objects within the sentence.
Spanish prepositions are invariable; they do NOT take on masculine and feminine or singular and plural. They will always have the same form. Prepositions can be single, formed by only one word, or complex, formed by more than one word. 
Single Prepositions
         a - at, to
a - at, to
	 ante - before, compared to
ante - before, compared to
	 bajo - under, below
bajo - under, below
	 con - with
con - with
         contra - against
contra - against
	 de - of, about
de - of, about
	 desde - since, from
desde - since, from
	 durante - during, for
durante - during, for
         en - in, on, into, by
en - in, on, into, by
	 entre - between, among, amongst
entre - between, among, amongst
	 excepto - with the exception of
excepto - with the exception of
	 hacia - towards, about, around
hacia - towards, about, around
         hasta - as far as, up to, until, till
hasta - as far as, up to, until, till
	 mediante - by means of
mediante - by means of
	 para - for, to, towards
para - for, to, towards
	 por - because of, to, for, by, through, per
por - because of, to, for, by, through, per
         salvo - except (for)
salvo - except (for)
	 según - according to, depending on
según - according to, depending on
	 sin - without
sin - without
	 sobre - on top of, over, above, about, upon
sobre - on top of, over, above, about, upon
         tras - behind, after
tras - behind, after
Complex Prepositions
       	 al lado de - beside
al lado de - beside
	 alrededor de - around, about
alrededor de - around, about
	 antes de - before
antes de - before
	 cerca de - near, close to
cerca de - near, close to
         debajo de  - under, underneath
debajo de  - under, underneath
	 delante de - in front of
delante de - in front of
	 dentro de  - in, inside, into, within
dentro de  - in, inside, into, within
	 después de  - after
después de  - after
         detrás de - behind
detrás de - behind
	 encima de - on top of, above
encima de - on top of, above
	 enfrente de  - opposite
enfrente de  - opposite
         frente a - opposite, towards
frente a - opposite, towards
	 fuera de - except for, apart from
fuera de - except for, apart from
	 junto a  - next to, right by, near
junto a  - next to, right by, near
	 lejos de - far away from
lejos de - far away from
Many verbs take in Spanish a different preposition than in English. Someverbs take a preposition in one language and none in the other, as:
- Depender de una promesa: To depend on a promise.
- Convenir en una transacción: To agree to a compromise.
- Confiar en un desconocido: To trust a perfect stranger.
- Regalarle un cheque: To present him with a cheque.
The use of the correct preposition according to the verb it follows is best learnt by practice. In the second part of the grammar, the student will be helped with a list of the most characteristic differences between the two languages. The Spanish construction is not quite so rigid in this respect as is the English.
Difference between "de" and "desde" both translating from--De mark the origin only, as: 
- Esta seda viene de Italia: This silk comes from Italy--it is Italian silk.
Desde calls attention to distance of time or space, as:
- Desde el 1° de Enero se estableció en comercio por cuenta propia: From the 1st of January, he started in business on his own account. 
- He viajado desde Londres hasta Calcuta en tantos días: I travelled from London to Calcutta in so many days.
The chief difficulty in the employment of the Spanish prepositions is the use of Por and Para:
Por is used:
1. To denote agency = by[2]; as:
- Es tenido en gran cuenta por sus amigos: He is thought much of by his friends.
- Este establecimiento fué fundado por mi bisabuelo: This establishment was founded by my great-grandfather.
Footnote 2: After the passive voice of verbs denoting mental action when formed by ser, Por is elegantly substituted by De, as: Son amados por or de sus padres (they are loved by their parents). But: Se aman por sus padres.
2. To denote the motive of an action, as:
- Lo hizo por envidia: He did it for (out of) envy.
3. To denote equivalency of any kind, as:
- Cinco peniques por libra: Fivepence for a pound--per pound.
- Trocar un producto por otro: To exchange one product for another.
- Considerar á uno bueno por £1,000: To consider somebody as good for £1,000.
- Por mejor le envié yo como viajante: I sent you to travel, holding you for a better man.
- Tienda por tienda, prefiero esta: Of the two shops I prefer this.
4. To denote distribution, as:
- Vinieron cinco por cinco: They came five by five.
Para is used:
1. To denote the object of an action (generally "to" or "in order to"), as:
- Trabajo para ganarme la vida: I work to (in order to) earn my living.
2. To denote destination (or direction), as:
- El tren sale para Valencia: The train leaves for Valencia.
- Esta cédula es para el Sr. Fulano: This warrant is for Mr. So-and-So.
- Voy para casa: I am going towards home.
Many idiomatic uses of Por and Para must be learnt by practice.