Ok I added all 4 to a order and clicked the checkout.
Got this window...
Gift Certificates and Coupons
You have the following coupons in your account:
BRY55MASTERS    Free Masters Series Item

I put the code in the right side but then at checkout I get this.
Charges and Discounts
Subtotal:    $49.92
Shipping (via ELECTRONIC):    $0.00
Tax:    $0.00
Coupon BRY55MASTERS:    -$12.48
Total:    $37.44
To be paid now:    $37.44

They are all tutorial too.

So I went back and only got "Bryce Masters Series: Cloud City" and now have...
To be paid now: $0.00

I keep getting this here below.
We had a problem processing your order. Please review your order and then click 'Place My Order' if ready.

Does this have something to do with the coupon and or the Paypal. I do not or have a every gotten and thing online but what is free.