When you first create an account with DealerWebsites.com, the login user name is email address that you first signed up with. You can create additional user accounts with other email addresses but if you want to change the default address, just do the following:
Go to the Settings section of the left side navigation menu and then click "Account". You should then be on the "Profile" tab at the top of the page.
Change the email address at the very bottom of the screen under Account Contact Information. Then click "Save" at the top right of the page.