How or where does a person add a picture in this forum?
Do you mean in a thread post? You can use the Upload button, 7th from the left in the row above the message space or you can just drag it in and drop it in your post.
If you look at the space where you type your message, before you type it, you’ll see that instructions are given for that. And I just dragged and dropped the screen shot from my desktop.
If you mean your profile picture, this can be done in the preferences: Click on your current logo at the top-right: