Help posting pictures

[stantheman55]

Sorry to ask a probably simple question …..But!
I looked for how to post a photo all I found was practice posting here. When I tried dragging a photo to where the main body of the text goes and release the photo, the photo goes full screen rather then showing as a Jpeg file or smaller picture in a text.
There is no way on the full screen photo to down size it to see any control tabs to activate or to change screens back to the original page showing the beginning of the original post.
So what am I doing wrong? If there is a segment on this site that shows how to do this I can’t find it and I am sure many other new-bees are scratching their head trying to figure this out.
I apologies in advance if this has been addressed before, as I have said I have looked but can’t find instructions. Any help would be grateful.
Stan.