Please help with "index.php?id=" <<<<<<<<<<

[Mess]

Hey, I'm new here !!!
Can someone help me with that please ???!?!?!!!!
I linked a link to "index.php?id=sitename" and what now... the site that should appear is done too.
But when I click that link nothing happens.

PLEASE HELP ME !!!

[Mess]

I found some things in the net but I don't get it at all