I'd check out this site, it has a step by step procedure you can follow : http://mysite.verizon.net/jazz.guitar/guitarsetup.htm .

Adjusting your truss rod wont lower your action, you have to lower the bridge or bridge saddles to do that. The truss rod is for getting rid of the fret buzz after adjusting string height. If its an Acoustic-electric, the bridges are usually set to a certain ehight and cannot be lower without taking the saddle piece out and sanding it. If thats the case, your best bet is to take it to a tech so your guitar doens't go outa whack.