Hello and welcome!
There are a couple ways to post pictures. If you have the picture posted on a picture hosting site, like imagestation, photoisland, etc, you can type the picture' s address in between and check on " click to upload" (down at the bottom of this window).
Or, if you have the picture saved on a disc, check " imbed picture in post" , and click on " click to upload" . A box will pop up. Click " browse" , select the picture you want from your disc, and hopefully it will be accepted. It will need to be 30kb or less to load from the disc.