You need a place to upload your pictures. If your ISP does not offer any webspace, try Photobucket, TinyPic or check out the topic; free web host with hotlinking? (for avatars) - some information may be out of date, as web hosts can change their policies or practices
From within DD, Ctrl-F11 will save a screenshot to the 'capture' subfolder (as a jpg in an unpatched game, in png format when updated), though this does not work during cutscenes or conversations. In general;