Tutorials for getting info from link

Hey guys. Im looking for some help with a problem I have:

Basicly, I have a page where it displays a bunch of characters, and these images are clickable. I have set the links up to something like:


I am just unsure what to put inside the characters.php to get the infomation from the link, like.

$id = (Some code here to get there $characterid from the link)

$id = $_GET[‘id’];