Hi Lissa,
If you click on the 'Paste Function' button (the one with the 'fx') on the
Standard toolbar, you can select any function and the 'Paste Function'
dialogue box will give a brief description of what the function does.
Double-click on a function and you'll get more help, including details about
each of the function's parameters when you select them. Click on the 'Help'
button on the dialogue box, and you'll get even more help, including
examples.
Cheers