It's possible to upload them as attachments and get them to show up full-size, but rarely worth the effort. Much easier to upload them to any of the dozen free websites that will host your pictures and provide you with the IMG code to cut-and-paste.
Here's an example of a picture hosted as a NES attachment, posted full size:
1. Add the picture as an attachment.
2. Preview your new post.
3. Click on the picture to view full-size, then right click on image and "Copy Image Location" (Firefox)
4. Go back into editor, click on the picture icon (the little tree in a box), and paste in the URL you just copied.
You can use a similar sequence of steps to re-use any image you've previously posted as an attachment, by going into your personal settings and clicking on "Attachments"
