Where to sell artwork?

Hi there everyone! How are you all doing? I hope you're doing great & staying safe :) I just had a quick question to ask. So my pp was asking me how he can get started on selling his artwork, he's such a talented artist! He wants to try and sell greeting cards that he makes like birthday cards, Mother's Day cards, etc etc. But he doesn't really know how to go about it so he asked me how to get started and to be honest I have no clue how to get started either? He's really passionate about what he does and I would love to help him get started! Could anyone help me or give me some advice on how I can get him set up with selling his artwork? Are there any specific websites that sell prison artwork or can I do it wherever? Also when he gets paid for it how can I send him the money that he makes from his sales? Please and thank you to anyone who can help me! I'd really love to set up something for him :)