Beginner fish owner

Does the sponge filter replace the hob filter or is it in addition to the hob filter? Thank you.

I currently have a Marineland Penguin power filter 150 with the bio wheel that the store recommended. After watching the Aquarium Co-Op video on upgrading your filter and replacing the throw away cartridges I decided that is the way to go. I want to purchase the Co-Op sponge pad coarse, bio rings and amonia filter pad to replace the disposable one. What order would I place the filter media for best results, or is there a better solution. Beginner here, not sure, any suggestions would be appreciated. Also recommendation on a better filter for a 20 gal. tank since I will be purchasing a new one and using the current as a backup. Thank you.