College courses to help prepare you for law:
If you're still in college, you can take writing courses. Being a lawyer involves a lot of writing. If your school has any prelaw courses or a business law or other course you can take that too.
You can also participate in mock trial or moot court through your college and practice legal reasoning, writing, argument, and public speaking.
Once you're done with college:
You have to go to law school to be a lawyer. It's called a juris doctor degree and takes 3 years full-time (usually) or 4 years part time.
To get into law school you first have to have a college degree, and you have to give them your LSAT (law school admission test) scores and write an essay.
Is that what you wanted to know? How to become a lawyer?