Right-click on your main iTunes folder (normally in User's Music unless you have relocated it) and click Properties, then go to the Security tab and click Advanced. The following process should install the correct permissions.
The error message 'The iTunes l file is locked, on a locked disk or you do not have write permission for this file' can also be a result of permissions problems. This can happen when a library is moved between computers or accessed by a different account on the same computer. If you are unable to edit tag information in iTunes it is likely that the files are marked as read-only or your account does not have the correct security permissions to make changes.
