The "progressive tenses" are formed using the formula below:

conjugation of estar + gerund = progressive tense

The gerund (present participle) is formed with the stem of the verb plus -ando (for -ar verbs) or -iendo (for -er and -ir verbs). For example:

hablar ---> hablando (talking)
comer ---> comiendo (eating)
vivir ---> viviendo (living)

Any tense of estar can be used to form a progressive tense. See the examples below:

Yo estoy trabajando en la oficina.
I am working in the office.

Yo estaba estudiando.
I was studying.

Él estuvo corriendo aquí ayer.
He was running here yesterday.

Note: The progressive tenses always refer to an action in progress. Be careful when you use the progressive to express a future action.

Estará él trabajando.
He will be working.