I think you have to use an image hosting service and paste in the link. Contrast with airgunwarriors where you can just copy and paste the picture directly into your post the same way you paste text. If I try that here, it shows up as I’m drafting my reply but then is lost when I submit it.
So when I post one here, I upload it to imgur and then paste in a link to it. Paste it as plain text and the picture will display inline in the post. If it pastes in as an underlined hyperlink, it will remain a link. Up above in the toolbar is a “break link” tool to drop the hyperlink if you need it.