Im having a hard time getting a job or getting into a trade school because of a conviction I had a few years ago ,how do I get it enspunged

Depending on what state you are living in, you can get either an expungement or a pardon. You will have to wait at least 9-10 years, have no subsequent convictions and consult with a criminal attorney to accomplish this. This process can take up to 8-9 months as well.

Agreed, many "unknowns"
Some states do not allow, in others some will require it to be 8 to 10 years after you finish with the punishment.

You hire an attorney and prove you have not gotten into any additional trouble, that you have held a steady job, maybe increased your education and more.