I moved this to Sandbox support since it is obviously a question, and not a post providing a tutorial or resource. The FAQ url should work, you should try it again when you have a chance.
If you download Master Chef Ogro, or run the RPG.bat in Sandbox 2.4 you will already have a health and mana bar (and experience bar in 2.4!). The code to create new spells is located in /data/game_rpg.cfg for both games. In both just scroll down to where you find the spells, you can even do a search. The 2.4 spells though are a little more complicated and a lot cooler

In 2.4.1 you'll even be able to use /testproj to try out different projectiles and see what ones you like and be able to copy the code to replicate the spell

Take care and I'm glad to hear you are enjoying Sandbox!
-mike