I found some information that let me limit Logon times for my son's account and to also to create a pop-up warning when there is 15 minutes (arbitrary) before forcibly logging them off. There is 2 things that I need to do before releasing Linux Mint as the sole OS.
1) How can I limit them with in the assigned login times to - say - 1 hour. then forcibly login them out. (Example; They can login anytime between 3:00pm and 9:00pm but for only an hour. That hour would be for the entire day. If they log out after being on for 45 minutes they can log back on but for only 15 more minutes.)
2) How can I install the glubble firefox extension once and have it be on all of the user accounts? When I install it it just shows up on my account.