Hi can anyone help me I got a 500 Credit Gift Card what do you do with it .

You can either sell it for sP or spend it on items in the Cash Shop. If you'd like to spend it, click on it in your inventory and click "Redeem Gift Card." Now it will be in your currencies and you can spend it :)

(Additionally, here`s the FAQ guide to the Cash Shop, just in case you need it)

If you want the csc, you can redeem it in the item's menu under "Other Options" after clicking it in your inventory. It'll then be available for you to use to buy things that cost csc.

Thank you was not sure what to do I think I will use it.