Damn man---are you trying to sound dumb deliberately or what??? There have been more articles written about how to spray paint than just about anything else that you can do to a car. Do a little bit of research before you get on here bleating about how "None of this means anything to you". You need a compressor with a regulator to regulate how much pressure the gun is going to receive from the compressor air tank. You need a spray gun, which you say you already have. Surely you must have some information about what pressure the regulator should be set at for the gun you are using. Buy a charcoal filter mask, and wear it whenever you are spraying paint so you don't kill yourself (nearly all paint is poisonous when inhaled in any concentration). Go to your local hardware store and buy some flat black Rustoleum enamel, or something along that line. Look at the instructions on the can, and it will tell you how much to thin it and what to thin it with. Either buy some paper filters, or steal an old pair of your wifes panty-hose to strain the mixed paint with just before you pour it into your gun cup. Don't think about hardners at this stage---you don't know enough to be using them, and for back yard paint jobs with hardware store paint, they're not necessary anyways. When you begin to use catalyzed paint from a body-shop supply house, then is the time to get into things like hardners. Reducers and thinners are both used to thin paint so that it can be sprayed. As a rule of thumb, reducers are used for enamels, and thinners are used with laquer based paints.----again, for what you are doing, read the instructions on the can. Be sure to buy a can of "gun cleaning thinners" to clean your spray gun with when you are all finished spraying. You can spray in your garage, but there is a real danger of fire and explosion, not to mention the stink----I am not going to even get into the use of ventilating fans, as they are only another source of spark, fire, and explosion.---Do it outside. Not in direct sunlight, not when wet, and not when the temperature is over 80 degrees f. Any fool can spray paint. I learned 40 years ago with a home made compressor and a $15 Sears gun, painting wrought iron railing. You will probably never be an expert spray painter, but you should be able to do a "backyard special".