To setup an account with Funambol, visit my.funambol.com and click the Sign up link.
From here, you need to choose the usual username, password etc as well as tell the software what mobile device you're using, your telephone number as well as your email account username and password.
Funambol uses secure data transfer methods so there shouldn't be too much concern about giving this information out - however if you do have these worries, use a secondary email account for testing the service.
Once this is setup, it's down to configure your device