To win, you have to control the largest portion of the world's population at the end of the game. You can take over a country in one of three ways: You can invade it, absorb it into your own country peacefully, or you can install a puppet government. Indicate what you wish to do, and I'll tell you whether or not your attempt succeeded. Invasions are the costliest method of takeover, but will almost never be undone, save for an invasion by another player; absorption is difficult, but is fairly successful and doesn't cost your country anything; and puppet governments are the easiest method, but the most prone to failure. You can invade, absorb, or puppet governmentalize other players as well, but absorption must be done with their consent.