Go to
http://www.taso.org and that will give you the list of contacts in the Dallas, Ft. Worth, and North Texas chapters. Also...go to
http://www.dallasref.com -- that is the website for the Dallas Chapter. The FW chapter used to have a site but it's been down for a year or so.
Just contact the chapter secretary of the chapters you want to be in. Keep in mind, Dallas is the 2nd largest chapter in Texas, so working your way up may be a little tough. Also--I'm in the Austin chapter right now (attending UT--Hook 'Em!) and we have just left TASO and are currently our own independent chapter. I don't know if other chapters are currently following this trend. I hope this helps and if you have any more questions, just let me know.