How do i get japanese and unreleased games on an american sega dreamcast?

i just bought a sega dreamcast on ebay yesterday, and i wanted to know how i can play japanese games like ikaruga and shenmue 2 on it. also, i wanted to get some unreleased games like propeller arena. i'm not interested in pirating or anything, and i wanna do this legitimately. my computer has windows vista if that helps. the dreamcast is an american one also. the dreamcast hasn't arrived yet, but it should be here soon. thank you for any help and God bless