I have a substantial amount of Ripple on Bittrex-i want to convert to bitcoin so i can then send to coin base and get some much needed cash.

i CANNOT find any instructions on how to sell/convert my Ripple to bitcoin on Bittrex.

I am relatively new to all of this and have just invested early and watched it grow but failed to get info on how to get my investment back. I know i can send my bitcoin from Bittrex back to Coinbase and then sell it for cash but i have no idea how to get it from Ripple to Bitcoin in bittrex to do so.

HELP