To resell any NFT bought from Collections on Gameflip, simply follow these steps:
1) On your profile menu, click on Gallery:
2) On your Gallery page, click on the 3 dots above the NFT you would like to sell and click on Sell:
3) On the listing details, you will be able to change the description and set your price for the NFT.
4) Once you are satisfied with all the details, just click on the Done button at the bottom of the page, and publish your listing!