To form the past tense you peel off the -ть from the dictionary form (the infinitive form) and add the suffix -л-, which renders the meaning 'past'. The resulting form is inflected for gender, with endings very much like noun endings: masculine -#, feminine -а, neuter -о, and Plural -и.
All past tense forms of all verbs have one of these four endings and there are no irregular verbs in this respect, although in some verbs the stress shifts, as illustrated below. (Some verbs are irregular with respect to the suffix -л-.)
Infinitive: предстђви-ть передђ-ть взї-ть
Past masc. предстђви-л передђ-л взї-л
Past fem. предстђви-ла переда-лђ взя-лђ
Past neut. предстђви-ло передђ-ло взї-ло
Past Plur. предстђви-ли передђ-ли взї-ли
The past tense agrees in gender and number with the Nominative subject of the sentence:
masc. Сђша передђл икрџ. Sasha passed the caviar.
fem. Мђша передалђ икрџ. Masha passed the caviar.
neut. Винћ стоїло на столљ. The wine was (standing) on the table.
Plur. Сђша и Мђша пќли винћ. Sasha and Masha were drinking wine.