Step 1: Sit in the driver's seat and locate the bonnet release lever. It is usually a small, black lever located to the left of the steering wheel, just below the dashboard.
Step 2: Pull the bonnet release lever towards you. The bonnet should pop up slightly.
Step 3: Get out of the car and walk to the front of the vehicle. Locate the bonnet catch on the front of the bonnet, in the center of the grille.
Step 4: Press down on the bonnet catch and lift the bonnet up until it is fully open.
Step 5: The bonnet is now open and you can access the engine compartment.
Note: Some Citroen C3 models may have a different bonnet release mechanism. Consult your owner's manual for specific instructions for your vehicle.