Actually, I'm not even sure how to get it from the trader to my wallet for that matter. (I'm sure it will be easy after the first time.) 
You just have to provide them with your wallet address and they'll send the coins to that address. Seems like you're new to crypto?
Btw, yes you can't exchange your BTC directly to fiat in Electrum. You'd have to send it to an exchange that supports fiat withdrawal. Most exchanges require KYC for fiat withdrawal, and you'd have to wait, maybe hours/days depends on what exchange you used.