A standard regulator should pretty much fit right on....then it is just an adapter to get the out valve on the regulator down to your air hose size. Should be able to get something like that at pretty much any DIY store.
If it isn't already fitted with a moisture trap, you might want to invest in a moisture trap/regulator, as the tanks can built up some decent moisture in them with the air under pressure.
Also, if the tank has a bleeder valve, it is a good idea to open it up and release the air in the tank when you are not using it. This will prolong the life of the tank, as air under compression in the tank will cause condensation in the tank....and what do you get with condensation on metal mixed with air? Rust. So relieving the pressure in the tank when not in use will help prevent rust build up in the tank, which can break loose and get in your airlines, but also rust out the tank.
