You have of store credit. To use it, simply place your order and you will be able to choose store credit as the payment method when it comes time to pay for your order.
The Pilot Varsity disposable fountain pen is probably the most recognized and popular fountain pen of its type. They actually have a nice nib and are fun to write with. If you're on the fence about investing in a "real" fountain pen, this is a great place to start!