Okay first make sure you have the correct GC code that is NOT expired (it will be the one that says it expires 11/30/2008)  Then copy the code exactly, no leading or trailing spaces..it has to be exact.  Put your items you want to purchase in your shopping cart.  Start the checkout process and on STEP 3 of the checkout process you will see this

Gift Certificate:           

A blank field will be beside the "GIFT CERTIFICATE" then an APPLY button.

I tried to copy and paste it so you would see exactly what it looks like but it wouldn't let me..sorry

Paste your Gift Certificate code in this field and hit the apply button.  You will see to the right where it puts the 5.00 to deduct from your order total.  If you owe anything after the 5.00 GC is applied you will pick at the bottom whatever payment method you are using to complete the rest of your payment (either paypal or credit card) then Place order!!

Let me know if you need more help.

Stacey