you cannot go around renaming accounts in OS X and expect everything to work. As an aside, you can't do that in Windows either.
Put that documents folder into the root of the HD.
Create yourself a new account, make sure you have admin rights.
Log out and then log into the new account.
The little house (the Home Folder icon) should have your name on it now.
Find the documents folder that you put into the root of the HD and drag it into your Documents folder.
All now should be good
I inherited a PowerBook G4, 10.3.9, from the previous person in this job. I set up my own user account and log-in. Then foolishly I decided to rename the little house icon folder from the previous owner's name to mine. Now when I use my log-in a clean desktop comes up. In the user's folder is the house icon folder with the previous owner's name, and a folder with my name. All my documents are in that folder, so I haven't lost anything. But how do I get computer to boot back into my account?