How to link the register and signup to another site.

Hello.
I have membership plugin installed. I have made a register page that shows what it costs and what you get. But it seems like the register to buddypress overtakes it to just register. means you can just register and dont se that things cost or nothing.
How to make it so you get to a register page and chose what memberhip you want before register.

http://www.outofthebox.no/english

Best regards
Morten