Need Advice on setting up member process

[Poolmandave]

I have developed a pool poll which sends the contents to my sites e-mail, closes the window and forwards the user to another page. Now that I have their contact information what would be the process to set up their membership? re: them paying initial dues and giving them some sort of automated member I.D. response. I would like them to use this I.D when purchasing. I might be approaching this in the wrong way. I would llike to receive their poll response, have them pay dues and get their member I.D. to them in one swoop but at this point I'm stuck. The way it is the user would have to fill out more pages. Please help.

http://www.swimmingpoolprofessor.com