The 2003 Chevy Tracker (depending on whether it has an automatic or manual transmission) doesn't have a dipstick for checking or adding transmission fluid like some older vehicles. The transmission fluid level is checked and filled by a mechanic using specialized equipment. There is no readily accessible filler port for the average driver.
Therefore, you should NOT attempt to add transmission fluid yourself. Improperly adding fluid can cause serious damage to the transmission. Take your Tracker to a qualified mechanic or transmission specialist for any transmission fluid checks or changes.