I think a screen capture using print screen, has to get "pasted" in a program like, for instance Paint, for you to view the screenshot...
I use MWsnap 3 for my screenies, you can get a similar program easily anywhere in the Web, it stores all the screenies in it´s own directory, sub-folder so you can acess them all later.
As to the posting of Screenies, here in the site it´s very easy, so step by step :
1- Registir in a site like imageshack or photobucket
2- Place your screenies on your albums, for instance Wells´s WW2 HoI2ARM Screenies, you can even decide whether you want your albums public or private. So this way you have your Screeenies in the Web now...
3- To place screenies from the Imageshack or Photobucket sites:
Post here has always, then use the insert image option provided in our "writing screen", copy the URL from the image hosting site, in the text "space" and then you have your post showing your Screenshot.