Hi. You have to upload the image to Dreamwidth separately and then embed it in your post. You can find the image upload tool in the "Create" menu on the Dreamwidth main page (see picture). After you upload your image, Dreamwidth provides a code you can use to embed it. That code will give you a tiny version of the image, but if you edit out "/100x100", then it will be full sized. It's kind of a hassle, but does work.