That's easy. As Mark says, just contact a local attorney or title company.
However, you (and the person already on title) should also check with an accountant as well. There are a lot of implications--more affecting the person already on title--to adding you to it.
And I'm not sure what your goal is, but there may be better ways of accomplishing it than adding your name to the title.
So, while the process is easy, first check to make sure that it's really in the best interests of you and the other person.
Hope that helps.