How do I set up a system password? I don't see that option on the Edit Site Pages. The options are at the bottom???

If you don't currently have a system password, the only way to create one is to temporarily restrict both the Class Profile List page AND the Missing page. When you do that, the system reminds you that there is no way for people to join unless you have a system password - and gives you the option to create one.
After that, you can un-restrict either or both of the Class Profile List and Missing pages, and you'll find the option to change (or remove) the system password at the bottom of the Edit Site Pages page.

thanks