Hey, I come from Shanghai.
It has always been a headache for me to teach Chinese kids about tenses, because you might know that there's no such a thing called tense in Chinese grammar.
Oh, grammar does exist in Chinese, and a lot for you to digest; however it is not a good idea for you to start Chinese learning with grammar. Were I you, I will begin with colloquial or everyday Chinese and practice Chinese with any native Chinese available.