A wiki I am an admin of, the Barbie girls Wiki (where I do fanfictions), has code where supposedly there is a left and right column. However, the right column seems to have been put on the left column instead. Could you tell me ways to solve the issue so it doesn't happen in that form of manner? Also, when I do visual editing, it shows the templates that are put together when they are supposed to be separate.
Stuff like this usually happens because you have an unclosed tag (like a <div> with no </div>) somewhere, so I would look for that. Since your main page is basically the column tags and a bunch of templates, check your templates.
In general, you always need a </div> after using <div>... that's just basic XML/HTML... you really shouldn't mess with code if you don't know that. The exception are self closing tags like <references />.