A good example of how test-driving first really is the way to go. 
You should be able to take a screenshot by bapping the PrtScrn key. It will save to your pictures. In your Post Reply window, you should see a toolbar at the top. It should have a talk-bubble, a B for bold, an I for Italics... You will see an Image Icon that looks like a double peak mountain. Click that to upload an Image to the thread.

