You will need to transfer the picture from you camera to your computer. I'm not familiar with that camera, so maybe someone that is can help you out there.
Once you get the picture transferred:
When you post a reply or a new message, there is a box at the bottom of the screen that reads "Attach file: Maximum size: 102400 bytes Valid file extensions: gif jpg png txt zip bmp jpeg" with a window next to it. Follow the window to the directory on your computer where the picture is stored and click on it. Save the message and the picture should show up in the message.
You may need to resize the picture or use some image compression software to reduce the size of the file under the maximum file size. There are a lot of different ways to accomplish this, including specific software designed for this purpose (Try x'sqeezeme! from
http://www.somewareonthe.net/).
Hope that helped some.