It's automatically applied when you check out. I just used mine when I ordered yesterday.
Castle Neu 1520 on 6S LiPo Powered Gmaxx (Nitro Killer)
Predator with OS .21TM
Supermaxx with Mach .26
Revo with OS .18TZ
Kyosho ST-RR Conversion
Ofna CR with Tekin ESC/Motor (2)
When you add items to the basket the points will be added (you'll see in the top right hand cornor of your page) but they are unable to be used until the cost is more than the points
That should get you $5, you can use that to buy anything that cost more then the value of your points. I cashed mine in and just got a balancing plug for my charger.