To Post a Screenshot of your work, create a own Thread in "Projects".
Before you could do that you need an image. Press the "print" Key on your Keyboard, open paint or your favourite Paint Program, Press STRG+V to paste the Screenshot, save it as JPEG.
Next step search for an hoster, maybe you could imageshack.us for this, after uploading, post the Image URL in your Thread.
eXample:
[ img]
http://www.my_free_image_hoster.com/Picture_URL.jpg[ /img] (write the IMG Tags without the space)
Write a little discription and press the Submit Button, thats it...
Sry for OT..
cYa Sebastian