STEP 1: Checkout Options(Register or returning customer)
STEP 2: Account and Billing Details(Name and whatnot)
STEP 3: Delivery Details(Probably address details)
STEP 4: Delivery Method(I guess shipping choices?)
STEP 5: PAYMENT METHOD(I'll bet you can choose paypal here)
STEP 6: Confirm Order(Is this your final answer?)
You have to go through the whole process. I have never ordered from them but most places let you choose paypal at the end of the checkout process. Don't worry, as long as you don't ever confirm a purchase you haven't locked yourself into a deal yet.
Hope that helps
Isaac