how to create a lock

So I want to now how to create a simple term lock, so I have to enter a code at startup to access my computer. Please help

There's a tutorial on the wiki for this. Well, it's actually a door lock, but you can change that so it doesn't open a door and just blocks the computer.
Also, you should post any question in the Ask a Pro forum, not here.

Thanks a lot .I meant to post it on the as a pro thing ,but I obviously didn't lol. I'm new to this, just joined thanks though