We replaced both of the tie rod ends recently- we bought some "beck arnley" brand replacements. Pretty much the same things, but i didn't like them as much as the OEM.
It's threaded on the tie rod, and locked in place or something with a bolt tightened up against it.
The tie rod end is pressed into the knuckle, or at least in there really tight... so it's helpful to rent a tie rod puller from an auto parts store like autozone.
The bolt on the OEM tie rod end that attaches it to the knuckle has a slot or a hole cut in it, and a castle nut threaded on it that's locked in place with a cotter pin. I like that method, but the replacements i bought didn't use the castle nut/cotter pin; they're just tightened down like a regular nut/bolt which is sort of difficult since as you tighten the nut the bolt just spins around in the tie rod end's ball joint. Seems cheaper to me too. I put 'em on, but i kept my old ones just in case i can still use them by replacing the boot. Something to note when looking at replacements