How do I use a pattern to unlock the phone screen?
From the home screen hit the menu button, then choose Settings > Location &amp; Security and from there you should have an option to set up a patter or pin based screenlock.  The pattern lock will give you the option to create your own pattern on the 3x3 grid:


If you want to be able to draw a completely random pattern, Cyanogenmod 6.2 has the option to draw any invisible Gesture to unlock the screen.