Welcome to TER.  I hope we get to see more of you figuratively and literally.

To post a photo, you must first get it up on the internet.  There are several sites that allow you to upload photos, drop box and photo bucket being two that I have heard of, and then when that is done, you cut and paste the photo's URL into the space provided when you start a post.

It would seem in fact that you have already mastered this given the photo that appears.