I know how easy it is, in FSX all you have to do is push "V" then it's saved into the "My Pictures" folder and in FS9, all you have to do is push "Print Screen" and then paste the pic into Paint and Save it!
Here's a couple I just took a few moments ago while on my P255 Character (please try to ignore the FSInn window):



Test Pilot
50 Hours x6
Green Monster x2
P001
October 2008 Screenshot Comp Winner
VATID: 1040117
Controller: UK Heathrow & Essex Region