On the client you don't see any volume or elsewhere? I think dexes are fairly experimental and not so trustworthy atm.

You could try a site like binance to convert (I've put a few btc on there and been able. To withdraw - not sure what their limit is now though). 

For stablecoins, a lot of them are on the ethereum network so you could go to myetherwallet or metamask (if typing into a search engine pick the first result that isn't an ad).

You're going to want to buy some ethereum at the same time and use it to fund the account you've just created as you need thst for PAYING FEES when you SEND a transaction from your new account.

If you're going to be doing this with what a hacker/scammer might consider valuable you light want to invest in a hardware device like a trezor (trezor.io) - alternatively there a guides for how to make one out of a raspberry pi using open source software for a few hundred bucks.