Just go to settings and scroll down to Glance. There you can set various notification settings etc. it also works with the MSN weather app (it'll display the weather info on glance screen) but only if you have the weather app set up as your lock screen also ( in lock screen settings).
"Peek" is the most popular setting. With peek, the Glance screen will come on according to signals from the proximity sensor. In other words, say you have your phone in your pocket (proximity sensor closed)... You pull your phone out of your pocket, (proximity sensor open) and Glance comes on.
It also works by just laying your phone down on a surface (table/desk etc) the glance screen will come on just by waving your hand over the phone (activating the proximity sensor) that way, if your hands are dirty, you don't have to touch your phone to see any missed calls, texts, emails, Skype messages, weather info, the list goes on...
Btw, welcome to the site, and the 1520 club! I love mine... and I LOVE Glance!