This info applies to Windows 7, and I understand it also works in Windows Vista.
Next, type in your new account name (John, The Laptop, etc…) and choose the account type “Standard user” (see note below). Now click the Create Account button. At this point you can add a password to your new account, or there are other options like managing other users. When you are done close the window and you’ve created your new user. Next time you start or reboot your computer, it will stop and let you choose which profile you wish to login with.
NOTE: Only choose an Administrator if you need to, and you understand exactly what that means. Otherwise you can end up with big trouble as you accidentally leave your computer less secure than it could be. If you needed a user with Administrator privileges you probably wouldn’t be reading this unless you need a refresher.