Newbie – problems with footer – please help

Hi all, I’m having a problem with the footer. At the moment I only have copyright info in there, I tried to change the size and background of the footer but it screwed up my page (how do I do this?). It looks fine as it is apart from on the first and last post when it jumps to under the menu. On posts where there is navigation both ways (prev post – next post) its ok. Also it jumps on the front page but not on the categorized or archive view. Can someone please help me? I’m doing this on localhost at the mo, not uploading till I have it finished.
Hoping this is easy!!!