Well, if you don't know how to redeem UGCs (Ultimate Game cards) this is the right thread for you.
1. Scratch off the PIN on the card
2. Go to Nexon.net
3. Log in
4. Press "Get NX"
5. Press "Purchase NX"
6. Scroll down or look down at the "Purchase NX" options
7. Press "PayByCash"
8. If you have a 20$ UGC press $10 (later on you can activate the code twice for 20k NX
9. Press "Proceed"
10. It will direct you to a purchase page where you enter your Email and PIN (on UGC card)
11. Press "Add Cart"
12. Confirm the purchase
13. Repeat the following instructions to receive another 10k (if you purchased $20 UGC)
14. Enjoy your NX.