As is the way with so many things in la vida loca it really depends on how much money you have got. The usual way would be to train for years and become a test pilot for a large morally corrupt western imperialist conglomerate such as Lockheed, then transfer to NASA and hope like hell you have ‘the right stuff’ and get selected for the astronaut training programme. Then slave away, until eventually you may or may not be lucky enough to be assigned a mission, on which you may or may not have your body parts distributed all over the southern skies as your shuttle vapourises in a bloody fireball. Alternately you could pay a fantastic sum of money to someone like Richard Branson for a ten minute trip with a group of capitalist pigs into near earth orbit (ie not really outer space at all) in a space plane type thing which hasn’t even been tested yet and will probably end up nose-diving into the Pacific. Personally if this was my ambition, I would either bribe some Russian to get me a place on the next trip to the ISS, or better yet actually hijack a space shuttle. Then you could go where you wanted – (apparently the Kuiper Belt is very nice this time of year).
Probably your best bet, assuming none of the above work for you, would be to buy as many skyrockets as you can afford, strap yourself to them, light the fuse and hope for the best. Or you could just give up and become an accountant.