After registering particident needs to be redirected

No after filling in username and 2x password participant gets to options: You can now update your details by going to the admin area of your account or go back to the homepage.

admin area: not enough rights to enter
homepage: i want them to my forum: http://www.mywebsite.com/forum/

I tried the redirected plugin, buts thats for login.

I use multisite