You have to access the Applications. It's been a while since I used my 300. Try hitting the blue button in conjunction with the Home button (right?).
From there you'll see the installed apps. You can also find a ton of applications online and games. You'll need to HotSync in order to install applications. Palm files are usually in the form of a .prc.
Hope this helps. Welcome to Everything Treo and congrats on your Treo 300! It served me well!
