Okies, copy the url of your homepage.

Then go back to where you bought the domain name.
I have a couple with 123-reg (or something).
I just visit their site, log-in, and find my user control panel.
Then I go to the section that controls where I want the domain re-direct ("Manage Domains / Web Forwarding") and just point the domain name to my homepage url by filling in the relevant address box.

Hope that helps.