Empire Earth 2?

Hi all, for those who know about Empire Earth 2, I have been playing this game for quite a long time, but I never knew how to make a new capitol "the building for creating new citizens" or to let a settlement prodice citizens. When I envade other opponents, I see that they have several of these buildings to make new citizens. If anyone have an idea about how to do that, I will be so grateful, thank you in advance.