If by pic you mean a picture or screen shot then all you have to do it press the PrtScrn/Print Screen button on your keyboard, usually to the right of F12. Once you have done that just open a paint project and press Ctrl+V and it will paste it there. Or you could use Fraps, in the Fraps window under the screen shot tab, you can assign any key you want to capture screen shots with. This is a bit easier because it saves them automatically to the Fraps folder in your program files, no need to save them individually. Hope that helped
You don't have to do the PrtScr, then individually use the Paint Program Ctrl V etc Step.
In IL2, each time you hit the PrtScr key, it will drop a *.TGA screencapture file/picture into your main (root) IL2 folder. Files are called GRAB0001.Tga, GRAB0002.tga, etc. You can take hundreds of captures/pictures if you want.
You can then load any/all of them into your Paint Application and convert to other formats, most usefully *.jpg files/images.
Note that every time you re-start IL2, your PrtScr captures will start over with the GRAB0001.tga file name again, overwriting any such previously named file which is still in the IL2 main/root folder.