There are several ways to post a picture here-
1) If the picture exists somewhere on the internet, right click on it, click Copy Image, and then in your message right click again and Paste. Size can then be adjusted by double-clicking on the image here and resetting the width to somewhere between 400-600 pixels.
2) If the image exists in your computer files, then click on the tiny icon across the top of the message window that looks like mountain (there is a chain link just to the left of it). A box opens and click the tab to upload it. (If you do not see the bunch of little boxes above the message posting window, then click on the Letter A inside a square and it should open what is called a WYSIWYG interface).
3) sometimes it is easier to upload your photo to an image hosting site like imgbb.com . After it's uploaded there, click on it first to open it in a new window, then right click on the image and click Copy Image. Then you can Paste it in your message here just like in option #1. Again you might need to adjust the size as described in #1.
4) If none of this works, or if you want an easier method, then you can always email it to me. Click the link at bottom of page to Contact Us, and I'll post into your message. Be sure to tell me your screen name and which topic it should be posted to.
It works better these ways than to use the attachment option below the message window.