Re: 2003 Crown Victoria "Check Engine" light is on when I am driving.
While you are at AutoZone, ask them if they have a manual covering CEL(CheckEngineLight) codes. Buy only if necessary and if it covers the codes, but seriously, let them get the codes and explain them for free if they can. I haven't looked in my Haynes manual to see if they cover all the codes or not. But, the reason AutoZone reads your codes for free is, they can look up the code, and tell you what parts you need, which makes them money. So one trip to AutoZone should do it. If they can't read the codes, have them direct you to a CodeReader that WILL work with your car. Most will have documentation telling you what codes mean what on your car.
Further, if you don't know a coolant resevoir from an oil dipstick, then you will most defininately need the most simple to use manual in order to attempt ANY repair yourself. Again, ask before you buy, which manual is the best for you, as most manuals assume that you have some experience with cars and repair. While at AutoZone, make sure that you have any specialty tools that you need to install / remove the parts that need replacing (if any). Some fuel and hydraulic components require special tools. If you buy any parts, ask them to come out to your car and show you where they go, and any tricks to repair. (NAPA is usually good for this if you buy your parts there).
Any parts store will sell you the correct antifreeze for your year and model, although it is getting easier these days to use one coolant. You can buy a hydrometer (If I recall right) to test your coolant to see if it is weak. Read the instructions. If it is brown and muddy like chocolate milk, you have a major problem and should proceed directly to a certified mechanic to have it diagnosed. This is not something you can fix with your experience level. If it is green and fairly clean (or orange and clean, although I don't think ours cars use that orange antifreeze), test it for how much protection it gives (how cold it can get before it freezes). If not cold enough, then take it to a 30 minute lube place and let them drain and recycle a little of your coolant, and add antifreeze until it does protect to the right temprature for your region.
Oil? Ask the AutoZone, NAPA, or 30 minute oil change place to look up which viscosity is right for your vehicle. If you just bought the car, have the oil and oil filter changed so that you KNOW that what is in there is good. As for brand of oil, that is personal preference although many will tell you that you should go with a 100% synthetic oil. Such as Mobil One or Pennzoil, or even Castrol Syntec. Do some reading on the subject and come to your own conclusions as to which brand is best for you. Good luck.
My job, basically is to think up Goofy Sh*t.