Die Vergangenheit auf -л/-ла/-ло/-ли

Here is a pleasant surprise: Russian has a single past tense form for each verb in each gender, and it does not care whether the subject is "I", "you" or "he". What it cares about is gender and number. The reason is historical: the form was once a participle, something like "having read", and participles agree like adjectives.

The recipe

Take the infinitive, drop -ть, add -л, -ла, -ло or -ли. Then match the subject: a man says Я был в Каза́ни; a woman says Я была́ в Каза́ни. The pronoun я does not change, the verb does. So a woman writing in Russian reveals her gender in every past-tense sentence, something English does not make you do.

Мы, вы and они take the plural -ли. So does polite вы even when you are speaking to one person: Вы бы́ли в Петербу́рге?

One past for many English tenses

English chooses between "I read", "I was reading", "I have read" and "I had read". Russian has one past tense; the difference between "was reading" and "have read" is made by the verb's aspect (чита́л versus прочита́л), which you will meet in the aspect topic.

Forms to learn by heart

A few common verbs do not follow the recipe: идти́ → шёл, шла, шли; мочь → мог, могла́; есть ("eat") → ел, е́ла; нести́ → нёс, несла́. Watch the stress too: in short verbs like быть, жить and дать it often moves to the ending in the feminine (была́, жила́, дала́).