If you're asking how to take screenshots in the first place, there are a couple ways:
- If you are on Windows Vista or Win 7, use the Snipping Tool which is built in.
- On earlier Windows, press Print Screen then paste in a graphics program.
- On other operating systems try pressing Print Screen or see if there is an app to help you. Google for details if you are stuck.
To put the image online, you can upload the images through an online image-hosting service. The easiest one is imgur.com as you don't need an account or anything.
To add an image to a post, click the Polaroid-looking icon on the tool bar and put the image URL (address) in. Note, this must the the actual image URL, not a page containing an image (like Google search results). The URL will usually end in .png, .jpg or .gif.
Comments are plain text only so just paste the URL and it will come up as a link, e.g. like http://img.pokemondb.net/artwork/scyther.jpg