New to Modding - Want to make Food Delivery Better

Hi everyone. I'm new to modding. I decided to start checking out modding TS4 because I hate the Zoomer's delivery service and I want to make it better or make a new delivery service altogether. I've started checking out the XML files (done so by using Carl's Sim Guides method of extracting and than searching the game files) so I think I have an understanding of how the delivery system works in the game. I'm just not sure how to manipulate it to form my own mod. I've also looked into Mod Constructor by Zerbu where I've figured out how to get the new phone interaction to appear on the phone but I don't know how to attach the delivery situation to the interaction.

I'd be so grateful if anyone can provide some direction or email me directly to try and help. My creator email is itsmaksimmy@gmail.com

Thanks!!!! <3