Editing users permissions so that users can edit listed items but not the sites look

im creating a sharepoint network for a big concern. What i want to do is simply give the users full permission when it comes to adding and editing documents. BUT, i do not want them to be able to edit the site itself. The problem seems to be that when editing the specific permissions the option that gives users permission to edit documents also includes editing the site. So my question is simply, is there a way to split theese or can i find a way around this?

Help would be appreciated.

EDIT: PROBLEM HAS BEEN SOLOVED