In Nigeria, if you wish to sell a $15 Xbox Live gift card, there are several steps you can take.

Firstly, you need to determine your target market. Look for gaming enthusiasts or those who frequently use Xbox services in your local area, whether through social media groups dedicated to gaming, local gaming forums, or by word-of-mouth within your gaming circles.
Secondly, set a reasonable price for the gift card. While it's a $15 card, consider factors like the convenience of digital transactions and the potential demand. You might want to offer it at a slightly discounted rate compared to its face value to make it more appealing to buyers.
Finally, ensure a secure and straightforward transaction process. Use reliable digital payment methods that both you and the buyer are comfortable with. Provide clear instructions on how to redeem the gift card once the payment is made. This helps build trust and encourages more people to consider buying from you in the future.