Some examples for diferent tenses I was reading:

I work as a programmer. I work on my own. I'm working in a new software for energy meter reading. I have worked in D.O.S. , but now I'm working on windows. 

I have spoken with some customers about my new software. If I had spoken years ago, I would developed it before.

I was watching tv when I had a call in my cell phone. My friend asked me to go to some place in the summer, so we are going to go to the beach., but after that, I know I will go to USA (but I don't know when yet). I'm sure I will have finished my work for my holidays.

Well, after this I should go to bed, because I have to get up early tomorrow. Bye!