hough77...I presume you may be new to kegging or thinking about getting in to it, so here is roughly how I keg my beer (please ignore if you already know this and I am assuming wrong).
Slow and steady way: I rack from my fermenter to my keg...put the keg in the refrigerator and attach the gas line...(optional) to set my rings and gaskets in my keg, I put my pressure up to 30psi for an hour and let it fill my keg...after an hour is up I come back and listen and look for hissing or bubbling...if there is hissing or bubbling then I have a leak, if not I move on....moving on I adjust my co2 pressure to recommended serving pressure (on the chart I linked in earlier post), which in most cases is between 10-12 psi, I then purge the keg (you do this buy pulling up on the pressure relief valve until all the sound stops), purging will release oxygen which is bad for your beer...with my co2 set at serving temperature, I leave my beer/co2 alone for at least 1 week then connect liquid post and enjoy!!!!
Quick and Impatient: Connect the co2 gas line to the out post (this is the side the liquid will come out of) it may be a little rough to get on and off the first few times you do this, but thats normal...with your gas line connected to the out post, turn you co2 on to 30 psi, wait until it stops filling the keg and purge...come back in an hour and purge again, leave for 24 to 48 hours...turn off co2, disconnect gas line and reconnect on in post (where the gas line normally goes), connect liquid post and enjoy!
The slow and steady way is just called carbing/kegging your beer....the Quick and Impatient way is called force carbing. You will read and hear a lot of people tell you to force carb by rolling or shaking your beer, but that way is almost a sure way to screw up your beer...if you would like an example of what shaking or rolling of a keg does to your beer, grab a can of beer and shake or roll it, carefully open it and pour it...I wouldnt be shocked if you had a glass of foam!
Happy Brewing!