help?

okay i feel like a total retard! buuut everytime i either try to download or just put in a code for my layout/template... it wont freakin do it! it says...

We were unable to save your template

Please correct the error below, and submit your template again.
Your template could not be parsed as it is not well-formed. Please make sure all XML elements are closed properly. XML error message: Content is not allowed in trailing section.

what am i doing wrong? somebody please help =(