Pause the game by pressing START, then press (X) + (Y).
When you want to save Hooper from prison, take two Commandos, one Tank, one Mobile Artillery, and two Bazookas. Send the rest to the outpost by the right slope to get on top of the hill. Wait until they start blowing it up. Then, take the remaining men you held and go to the base. Blow up the prison with Commandos. There will be no men or machine gun bunkers. Then, send him to the flag at the northeast village. Do not worry -- there will be one or two men, but Hooper is strong and will make it without fighting.