The following regards posting pictures stored on your computer. It is NOT the second method of storing them off site and pointing those pictures to load from that alternative location.
First don't use the "Quick Reply" at the bottom of the page. Rather use the "Reply" at the lower right of the post.
When you are ready to add pictures click on "Choose File" under "Attach:" The pictures will need to have already been on your computer in a known location (I recommend you create a folder titled "Pinto Pictures" and store all your car pictures there). The prompt window will allow you to navigate to that stored location. Once you find the picture click on it and then click on "Open" in the lower right.
To add more pictures click on "(more attachments)" and repeat the process. There is a limit of four pictures and a files size limit of each picture. If you find the file size too large the fastest way (I know of) is to use the Snipping Tool on a presented picture and save that. It creates a smaller file size that I have never had a problem posting. I recommend that you note it is the smaller version when you name the saved snip so it is not confused with the larger file.