First you need to login to your normal account or an account with administrative privileges.
Click on Start, then click on Run and type the following command line and press OK:
“Control Userpasswords2”
This will bring up a User Accounts window, in this window you need to untick ‘Users must enter a user name and password to use this computer.’ Click Apply and OK
Now choose which account will be automatically logged on by entering the user name and the password (if the account has one).