Locate a professional fastpitch softball team in your area. The National Pro Fastpitch Website is one way to find these teams. The Softball Search website also offers the same information, with a little more detail.
Contact the president or owner of the team and find out when tryouts are held and what you will need to bring to the tryouts. You can count on bringing proper softball clothes such as shorts and a t-shirt, cleats, bat, glove, and documentation of a recent physical exam.
Practice everyday and get into the best shape you possibly can before the tryouts. It would be a good idea to hire a sport-specific personal trainer to get you ready for this big opportunity.
Try out for the team. Do your absolute best regardless of what position they may put you in. Even if you do not have the best skills, work hard, and never give up on a play and the owners and coaches will notice this about you.
Wait to hear from the team about whether you made the team or not. If you have not heard from the team within a week of trying out, contact them to see if they have made a decision.