Ok, i believe that i had the same problem as you have. I'm not sure which code you're looking for, but if you're looking for the serial number or the product key, you need to reigster at students.autodesk.com ; or by searching autodesk first base into google and clicking the first link. After you register and log back in, you'll need to click get software. Once you select the AutoCAD Inventor Professional Suite 2011 English 32 or 64-bit, you should receive a product key and serial number (you might have to fill out a bit more information before you get it, i don't fully remember). If you are looking for the activation code, then send me a Personal Message on Chief Delphi, because you have to send an email with a bunch of information that would take too much space up on a post
Hope this helps,
-Duke
P.S. If this was not what you were looking for, please try and describe further what the problem is.