Step # 1. First select the picture you want to post and make sure it is added to your wordpress media.
Step # 2. How do you add picture to your wordpress media you click on +Add on top right and select Media .. See picture below.
Step # 3. Than it takes you to a page where you click on Add New see picture below that will allow you to browse on your computer for the picture you want to add to your wordpress MEDIA
Step # 4 Once you added picture to media, all you do is go back to step one, but you will select the picture from your media this time to add on your post.
I followed the steps above and it was how I was able to add the picture below.