How do i change spark plugs on a 2003 chevy tracker?

I don't know if your vehicle is a 4 cylinder or 6 cylinder. This will make a difference in the # of cylinders as well as the placement. If it is the 4 c ylinder when you open the hood it says at Autozone.com that the spark plugs are on the front of the motor lined up 1-4. If it is the 6 cylinder then you will have 3 at the front of the motor and 3 at the back of the motor. Regardless it is the same concept. I don't know for this particular vehicle, but it is possible you may have to remove a large plastic engine covering in order to access the spark plugs. What I recommend is to replace the spark plug wires at the same time as the plugs. For all my vehicles I use NGK plugs and NAPA auto parts has the best plug wires I have used - Belden Maxx. Prior to starting you will want to check the "GAP" on each new spark plug. Using a spark plug gap tool available at parts places for about $1. Take the new plug and the non-porcelin end (the end that has the arc) insert the arc into the gap tool at the lowest end and slide the plug around until you reach the corresponding "GAP". For this vehicle it should be .44" (I checked on Autozone's website but you may want to check to be sure. At some of the part's places they may tell you that you don't have to check the gap, but believe me you alway's should. I just did a car where they insisted that I didn't need to check the gap and each plug was not gapped properly. The Arc on the plug has to be specific for your vehicle or you will have too much spark or not enough. After gapping the new plugs you are ready to start. Somewhere on the side of the motor you should see either 4 or 6 wires/cables branching out to the cylinders. Starting with whichever you prefer (do only one at a time to avoid confusion) trace the wire/cable to the cylinder and where it goes to the cylinder a "boot" covers the spark plug. Twist the boot until it comes off . If you are going to replace the plug wires take that one off and match it up to your new set (They will be different lengths). You will need a ratchet and a spark plug socket (available at parts places) The spark plug socket has rubber on the inside to protect the porcelin of the spark plug, and to provide grip. You may or may not need a small extension. Place the spark plug socket over the end of the spark plug and apply pressure until the spark plug begins to loosen. You may have to apply quite a bit of pressure if they are in there tight. Once it is loosened take the old plug out, and place the new plug in the spark plug socket. Don't use the ratchet at this point, just begin to thread the plug in by hand once it is in there as much as you can get it, tighten it down with the ratchet making sure not to over-tighten. Do the other cylinders in the same manner.