Do the following:
1. Take the Basic Rider's Course (BRC) from the Motorcycle Safety Foundation (MSF). You should have one in your local area. Best of all, they supply the motorcycles for you to learn on. In some states, taking this course will get you most of the way to obtain a motorcycle endorsement on your drivers license.
Here are course offerings in Georgia:
or call 1-800-CCRIDER.
2. Go to your library or bookstore and get the book, "Proficient Motorcycling"
by David L. Hough. Read it. Don't let the technical stuff in the front section ("rake", "trail", blah blah blah) keep you from reading the whole book. There is a lot of very good stuff in there, and it may save your life someday. Proficient Motorcycling
should be mandatory reading for all riders.
3. Start out by buying a used bike and ride it for a while. "A while" means a year or so. As recommended above, a 250 cc bike is ideal. Don't get anything larger than 600 cc (which is too much!) - your eyes will want more, but don't give in to temptation. While you are learning and internalizing
the basic skills, you can be choosing your next bike. That next bike may be the BMW bike that you want. The first bike may not - don't sweat it.
In the meantime, we are here when you have questions. The people here are great, and are happy to help. You don't need to be riding a BMW to stick around.