There are two ways:
1. The quick and dirty way is to "attach" photos to your post. When bring up the editor to do a post, right below the editor is a "upload attachment" option where you can select files. The downside to this is that it will crop or resize your photos into something quite small. Plus is will put some undesirable text around it. It generally looks pretty crappy, but it's very straightforward and quick to do.
2. The better way is to post your photos on some sharing site, like imageshack and lots of others. Then you just link to it in your post. I posted some instructions on how to do this in the sticky on the "Gallery" section.
You can find it here:
viewtopic.php?f=11&t=21658And just ask if you have trouble.