Pete, a big welcome to you to Seven Forums!
If you are talking about what I think you are talking about, the window that pops up after a windows installation, then there should be a small box on the far bottom left (hard to see) to uncheck that will keep it from popping up any more.
If you want to hide the screen where you enter your password and have you automatically log on, see this: Log On Automatically at Startup
In addition, you can set the computer to require or not require a password when it wakes up from sleep: Password - Require on Wakeup
Hope this answers your question.