you're just about there. Ok so if you have your photos uploaded somewhere right click on your photo, go to properties and copy the address which will end in .jpg or .bmp Then when posting here click on the yellow photo icon and insert paste the address into the popup (which I think you've already got the hang of). Then your photo will appear.
If you are just posting an address, click on the "earth" icon
and your link will appear as "clickable" that people can go to.