The imperfect tense of haber is había.

Sentences using haber in the imperfect tense

Había may be used:

to express existence

Había catorce llaves en la mesa.
     There were 14 keys on the table.

Había un problema muy grave.
     There was a very serious problem.

¿Había algunos testigos?
     Were there any witnesses?

Había mucha cola.
     There was a long line.

Había unas treintas personas.
     There were about thirty people.

to indicate obligation

We usually use the formula había + que + infinitive

Había que cerrar el portón.
It was necessary to close the gate.

Había que pagar la mensualidad.
It was necessary to pay the monthly fee.

Había que comprar vegetales.
It was necessary to buy vegetables.

Había que tomar precauciones.
It was necessary to take precautions.

The verb haber has other uses which will be very important when you study intermediate Spanish.

to form the perfect tenses

¿Has aprendido muchas palabras?

Have you learned lots of words?

No hay de que.

You're welcome.