To be certain, you should:
* Consult your owner's manual: This is the best resource for precise location information specific to your vehicle.
* Check online repair manuals: Sites like Chilton or Haynes offer detailed diagrams showing the location of various components, including the EVAP canister. You'll likely need to provide your vehicle's VIN for the most accurate information.
* Search online for images: A Google image search for "2004 Chevy Cavalier EVAP canister location" might reveal pictures showing its location on similar models.
Keep in mind that working under a car can be dangerous. Use jack stands to safely support the vehicle and wear appropriate safety gear.