Can someone tell me how trading with other players work in a single-player game, please?
I would love for someone to send me a spark thrower and a flame thrower rifle Just to see how it works. I have not finished the main story yet so I can’t go into the zome where these rifles drop. The mobs are bog creatures or something.
Welcome to the forum. 
It’s peer to peer so you either host a game or join one.
Best is to ask in one of these threads depending on whether you’re playing softcore or hardcore.