how to have home page as a sign up page

I am currently using the dolphin to build a social community....

But there is a big problem... I want to have my sign up form(customised ) at the homepage and only members who sign up can see the whole website...

just like orkut.... for example http://www.kirkal.com ..

They have sign up form at their homepage..... getting more people sign up to their community.... and then members can see the website....

Could anyone help me out......

I can help you, I got this on my site, easy to do but many steps.

let me know if you want my help via private message