Originally Posted by viki

Are you the owner of the blog or do you just have an account there? If you just have an account, you may not be able to see all options.

If you're the owner, then login to admin and scroll down to the bottom to check what version you're running. If it's 1.5+, you should have a presentation tab on the top menu. Even earlier versions may but I don't have experience with those.

Regardless, you can always FTP to the aforementioned dir to find all the template files including sidebar.php or something similar.