Well I was gifted a 500 Credit Gift Card and well I know nothing about it. What am I supposed to do with it? Or more like how do I use it?

You have the option to 'use item' when you click on the gift card, it will give you 500 CSC(cash shop credits). You can spend these in the cash shop!

https://subeta.net/cashshop.php

Oh! Okay. Thanks! I feel so silly.

You're welcome and no worries!

Also, these credits never expire nor do the cards so you can hang onto either as long as you'd like.

Okay. Thank you!