and upload the pic there. THEN put the link to the pic in the body of your post. In other words, you cannot really post a photo. Just a link to one on the internet.

I could have sworn we could do this umpteen years ago when I was first here.

right click the image from another website and, then click "copy image location" then paste it into your post. do "preview" to make sure it works then post.

if the image is something saved to your computer you need to upload it to a hosting site as mentioned by others

Cut and paste?

I bet there are programs out there where you can create your own ones, but I have never done it.

Then save it to a site like photobucket and then paste the link to DU.

Or a Sharpie