Its a tga file. Any paint program that can handle tga files can print it. Try going to the tga files in the maps directory of Dominions2, and double-clicking a tga file to see if your machine knows of a program on your machie that can view it. Then see if the FILE menu has a print option.
If your paint program doesnt then you might want to get a viewer program that can print. For WIndows I recommend Irfanview which you can get
HERE. Its a free program with a ton of options.
If you are trying to print a map from within the game (with all the flags and stuff to show whats going on) that involves using the Print Screen key and your paint program.