John - congratulations! The 175 is a good airbrush... I have that one as well as the Badger 155 and Iwata HP-CR and after the HP-CR I use the 175 second most.
You'll need a regulator at the least, you can get one at most hardware stores and even Wal Mart if you have one near. They have larger graduations to the markings (from 2.5 to 5psi per mark) than the hobby style ones but it still works, you might want to check out a real hobby regulator though as I think eventually you will want more control over how much PSI you use (the marks are 1psi increments). If you have a Hobby Lobby nearby they have them (complete with built in water trap) for about $40 I believe. The ones at the hardware stores are about $25 with $15 or so for a watertrap so they are about the same price.
Speaking of water traps, unless you live in a rather dry area (like New Mexico or such) you'll want to get one. Nothin ruins a good paint job like a stray drop of water coming from your airbrush.
Besides that, just paint and something to paint it on as well as the appropriate thinner and you'll be airbrushing away!!!
Good luck to you and if you need anything else dont be afraid to ask!!!