You can consult here http://www.guidetojapanese.org/learn/grammar It's a rather complicated grammar, can't be answered in several words.

The many forms of conjugating japanese verbs can express simple past tense simple present tense* future tense* present perfect tense** present continuous tense** present perfect continuous tense all phrases can be expressed in negative, affirmative or interrogative. *the simple present tense and the future tense are expressed by the same conjugation, being understandable by context. **the present continuous tense and the present perfect tense are expressed by the same conjugation, being understandable by context. Some examples: Simple past tense: Kinou, gakkou he ikimashita/ikimasen deshita/ikimashita ka. (verb iku) (He went/didn't go/Did he go/ to school yesterday./?) *Simple present tense: Mai nichi, gakkou he ikimasu/ikimasen/ikimasu ka. (verb iku) (He goes/doesn't go/Does he go/to school everyday./?) *Future tense: Ashita, gakkou he ikimasu/ikimasen/ikimasu ka. (verb iku) (He is going/isn't going/Is he going/to go to school tomorrow./?) **Present perfect tense: Gakkou he itteimasu/itteimasen/itteimasuka ka. (verb iku) (He has/hasn't/Has he/gone to school./?) **Present continuous tense: Heya wo katazuketeimasu/katazeuketeimasen/ katazuketeimasu ka. (Verb katazukeru) (He is cleaning/isn't cleaning/Is he cleaning/his room./?) Present perfect continuous tense: Juu nen kan, eigo wo benkyou shitekimashita./ benkyou shitekimasen deshita./benkyou shitekimashita ka. (verb benkyou suru) (He has been/hasn't been/Has he been/studying English for ten years./?)