You don't have to have a photo host to post pictures here. It's one option, but not a requirement.
Just to your right of the the Image Edit popup URL field is a widget to Browse for pictures on your computer. Click on that and you will see another dialog for uploading images. There is another Browse button on this dialog, which will pop up a standard file search dialog for your computer.
Click through your computer folders and find the image you want (I use View Thumbnails under XP to see the pictures I'm browsing). Click on a picture from your drive folder, and you will be taken back to the Upload dialog with the location of the file you clicked on showing in the Browse field. Click on Upload to get it into your RoboCommunity workspace.
You can add multiple files to your RoboCommunity upload work space by using the drive Browse and Upload dialog multiple times.
Once you have the pictures uploaded that you want, click on a thumbnail for one of the uploaded pictures, and you will be taken back to the orginal Image Edit dialog with the file name filled in.
Finally, click on Insert Image and the image will be shown in the post you are editing.
Not as simple as some photo upload dialogs I've see, but not too complicated, either.