If the cartridge is successfully installed, it will be flush with the pile. For an extra measure you can push the cartridge inward, but do not use a lot of force.

The front end of the cartridge will be able to determine the temperature of your water. Pull the plastic toward yourself, and turn it to the right for cold water, and to the left for hot water. You can also keep the plastic in the middle, but the temperature of the water will be less accurate. This means it will either be too cold or too hot.