How do I see screenshots taken through Steam of a non-Steam game?
Steam has an option to take a screenshot of your current game at any time (F12). For Steamworks games, all screenshots are displayed as thumbnails on the library page when I select the game in my library, but when I take screenshots of a non-Steam game, they don't appear on my profile page. The profile page also says I have 0 screenshots for that game.
How do I find them? And how do I make them show up on my online profile page?
Right click on the game name in your library and choose 'view screenshots'.
Steam doesn't know what to do with non-Steam games other than run them, and use the overlay on them (sometimes), so it doesn't show any images or other data about the game in the library.
To add these screenshots (or any others) to your profile page online, select the image in the 'screenshot viewer' using the step above, and then click the 'upload' button on the right.