You are not stupid, you are a bright person. Medium has tried the patience of many others before. And I missed a step, which was Start a Story and write anything (because yeah, when you mentioned that error message I remember the same thing happened to me when I tried to start a story with a photo — the Medium editor doesn’t like that). So next, start with a title (type something, but before you hit return make sure to tap the double-T icon on the left side of the menu — tap once for Title, again for Subtitle, again to make it regular text), go to the next line, and try to add a picture again. Practice by adding a photo to your reply to me. DO NOT GIVE UP!
And I like your rambling stories. Why do you think I want you to publish them?