You can insert an image or attach a file by clicking the upload icon () in the editor. Only certain file types are allowed, but we think we’ve included all of the ones people need.
If you have trouble, reply here to let us know.
Also, if you have an image on your clipboard, you can paste it in to the editor, just as you would in your word processor. When you paste it (CTRL+v or ⌘+v) and the file will upload and be inserted into your post.