Get yourself a repair manual (Haynes, Chiltons, ect). It will explain the process in far better detail than most any online thread that you'll find, but I'll break it down in a simplified manner.
Basically, unbolt the driveshafts from the t-case (probably don't need to remove them completely but it would give you more space), remove the crossmembers/skidplate under the tranny and t-case (and get a floorjack under it, preferably with a ratchet strap around to hold the transmission to the jack), remove the starter, undo the console around the shifter and pull it up and undo the 4 bolts that hold the shifter down and t-case linkage if its a manual shift, undo any wiring that's attached to the tranny/t-case, possibly might need to undo the breather lines but they're probably attached to the tranny anyways, unbolt the bolts that hold the transmission to the engine, and slide it back and down - careful though cause it all weighs a couple hundred pounds easily. You *might* have some issues with clearing the exhaust, just something to keep in mind.
Next you need to unbolt the pressure plate from the flywheel and toss it in the scrap metal pile (unless you need to return it for a core), and undo the 6 bolts holding the flywheel on and take it in to a machine shop to get it turned. Since you're in there anyways, do yourself a HUGE favour and get a new slave cylinder for the clutch and replace it since you're already in there. If its not dead now then it'll most likely die half way through this clutch and you need to remove the tranny again to replace it - they're prone to failure.
To install the tranny, basically reverse those steps for the most part. This is an extremely simplified set of installation instructions but thats the general gist of what's involved. It also helps to get someone to give you a hand, and expect this to take at least a very full day, possibly two since you have to remove the flywheel first to get it machined (trust me, don't skip doing this otherwise you run the risk of you new clutch not working properly). Its not overly tough, but you'll probably be dealing with rusted or sticky bolts underneath, and it can sometimes be a bit of a pain lining the clutch and transmission back up. Its critical to torque the pressureplate bolts to spec so they don't loosen off on you later on (I had a Toyota 4x4 do this to me once, very annoying - live and learn). A bit of Locktite doesn't hurt either.
Hope this helps, and good luck. LR
'09 Ford Ranger FX4 that gets abused a lot... but doesn't like to swim though.