The icons at the top of this window when you are adding a post? Click on the small "paper clip".
A window will appear in the upper left. "Browse" you hard drive for the photo(s) and click up load. Do this for as many pics as you want to post. Once you have downloaded them, at the bottom of that window "Close Window".
Click on the "Paper Clip" again and it will say, "Manage Attachments". Double click the file name of the picture you want to insert first. A code will appear. Once you post the thread, the picture will appear.
If the photo is located someplace else on the Internet -
Looking again at the icons at the top of this window, click on the small box that looks like mountains in the back ground. If you hover your cursor over it, it will say "insert image".
Click on that icon and inter the URL location of that photo. The easiest way to get that URL is to go to the location of the photo and "right click" on the picture.
Scroll down and/or look for "properties". Click on "properties". In that window will be the URL. Copy that info and paste it back into the address box that is made available at this site for "insert image".