Do your self a favor and find a pro shop. They will be able to find out what string you need or take the string off and measure it so they can come up with something that will work good for that bow.
While I don't doubt that they guy at gander had some knowledge, I think you will be pleasantly surprised by a quality pro shop.
Will second the need for practice, you cant just sight you bow in and forget about it. If you want to have success you need to shoot quite a bit. Out door 3D shoots are a great fun and a great tool for learning to shoot.
* (Swinging club) Whack! whack! whack! *
Nope, the old nag's still dead .