I want to lve with my dad but my mom has custody what do I do

How old are you?

I suggest first talking to both of your parents and let them know your concerns and see if they are willing to work with you without having to go through the courts. If not, you have the right to be heard, so you can put a request in to the Friend of the Court.

Tell you mum or dad... or both

Your dad will have to file for cusotdy in court, depending on your age, they may allow you to testify. But they will look at many more factors than just what you want also.