Welcome Kaffa!
I can't speak for other operating systems, but in windows, you use the printscreen key (PrtScrn), then paste into your favorite image editing program (or ms paint in a pinch).
Or, if you are running dominions in a window, you can use ALT+PRINTSCR and it will only capture the window with the focus instead of picking up the entire screen.
Hope that helps.
(Your English is better than mine and it's the only language that I know!
)