Need some basic vBulletin programming advice

[subnet_rx]

I've used Gary's tutorial to create a basic vB page. Pretty easy. I know PHP and now would just like to take a script and put it into this page. The script would take in data through a form, and put it into a database (hopefully separate from vB because I'd rather not grow that db any larger). I don't need to edit any templates, and shouldn't have to work with any vb functions with exception of logging who the person is inputting the data and maybe some usergroup permissions.

I'd like it to work a lot like the vBookie script where a certain usergroup can input games, and everyone else can pick winners/losers. I don't want to give them credits or even keep up with scores, just keep up with how many of your picks won and how many lost. I can figure out how to build this fairly easily, but sticking it inside vB is not something I'm familiar with. Where would my functions go? How do I call the result data of these functions in the template? Can I connect and make SQL calls on the db just like a regular php script?