If you don't have a photo hosting service (photobucket, pbase,flckr,etc) look at the top menu. Goto the "Photo Gallery", create an account and follow the directions to upload a picture (located on your hdd) to the gallery here.
Once you've uploaded a picture or two and created your gallery, you can link a picture from your newly created gallery and imbed them in post by doing the following.
From within your gallery, open the picture.
Right click on it. From the resulting drop menu select "properties"
From the resulting window highlight and copy the entire url
In the thread your creating, below the subject bar, locate and click on the button "IMG". You'll see
hit preview to be safe, then enter
This is a photo from the gallery I have here