how does swaging work

:Fire:how does swaging work? I am considering purchaseing mr. blackmons die for make .223 jackets from .22. however i have a terminal case of dumb ass and cannot understand how it works. I mean i can see how the jacket is made but how do you fill it? do i have to buy a mould and cast cores then somehow insert them into the jacket? or do you place the jacket into a mould and then somehow fill it with lead. Please help! I am so con:(:Fire:fused!

Here's a link to a post I wrote several years ago.....lots of good reading and pictures.

http://reloaders.gunloads.com/showthread.php?t=288