The :guilabel:`mode` drop down has 4 settings Disable turns off the screensaver, blank screen only just turns the screen itself off, one screensaver sets one screensaver, and random screensaver selects a random screensaver. To set how long it takes your screen to go to the screensaver change the field that says :guilabel:`blank after` to the number of minutres you want the system to be idle before starting the screensaver. If you have a random screensaver set you can change with the number of minutes it says with cycle after for when the screensaver will change to another one. The checkbox for :guilabel:`lock screen after` takes the number of minutes to lock the screen and the number of minutes is how many minutes it takes to lock the screen.
