Past is generally expressed by the suffix -л- on a Perfective or Imperfective verb.
Present can be expressed only by the non-past endings on an Imperfective verb.
Future is expressed by non-past endings on a Perfective verb and by the non-past forms of the auxiliary verb бџдут with the infinitive of an Imperfective verb.
  Imperfective Perfective
Infinitive писђть написђть
Past писђл написђл
Present пќшут ———
Future бџдут писђть напќшут
The past and future forms of the verb бІть "to be" are used in a variety of constructions to convey the time of the event.
Past У менї нљ было дљнег. "I had no money."
Present У менї нљт дљнег. "I have no money."
Future У менї не бџдет дљнег. "I'll have no money."
Past Мнљ бІло хћлодно. "I was cold."
Present Мнљ хћлодно. "I am cold."
Future Мнљ бџдет хћлодно. "I'll be cold."
Past Мнљ нужнІ бІли дљньги. "I needed money."
Present Мнљ нужнІ дљньги. "I need money."
Future Мнљ нужнІ бџдут дљньги. "I'll need money."