Use of the imperfect
     To describe a situation or habitual action in the past, use the imperfect.

Formation of the imperfect
     All French imperfects (with the single exception of être) are formed regularly off the stem of the first person plural (the "nous" form) less the ending -ons, to which you add the endings -ais, -ais, -ait, -ions, -iez, -aient.
     So the imperfect of parler would be: nous parlons > parl--ons> parl--> je parlais, tu parlais, etc.
     The imperfect of finir would be: nous finissons> finiss--ons> finiss--> je finissais, tu finissais, etc.
     The imperfect of rendre would be: nous rendons > rend--ons> rend--> je rendais, tu rendais, etc.

     Even irregular verbs are regular in the imperfect. For example, j'avais (nous av--ons), tu faisais (nous fais--ons), il allait (nous all--ons), nous disions (nous dis--ons), vous buviez (nous buv---ons), elles venaient (nous ven--ons).

     Etre has the only irregular imperfect stem, ét--. So the imperfect would be J'étais, tu étais, etc.

Le and certain expressions of time
     Notice the use of the definite article le without a proposition in the French equivalent of on the weekend: le week-end. Similarly, for in the morning, in the afternoon, in the evening, and at night, the French would be: le matin, l'après-midi, le soir, la nuit.