To attach a screen shot, use the image button, which is the 3rd icon from the left above the window when you post a message. Please note the the image must be located on the internet, as clicking that icon will prompt you for a URL.
If the image is on your computer, you will have to upload it to the internet first. There are a number of image hosting sites that are free to use.
We might be able to figure this out with the screen shot you mentioned earlier.
