how do I sell it ?
Depending on what country you're in, but personally I'd go with Binance[1]. Create an account, send the BCH over, and sell it for BTC.
And of course, make sure to withdraw the BTC after and store it on a reputable wallet.
[General] Bitcoin Wallets - Which, what, why?:
https://bitcointalk.org/index.php?topic=1631151.0
[1]
https://binance.com/That's my problem. I can only send the BCH from the mobile app and my wallet is empty.