To make a mod, create a class extending Mod (com.wearedevs.someclicker.mod.Mod). In the constructor of your new class will contain all the code that is run (Registering Handlers and Shop Items).

package com.imdaveead.someclicker.examplemod;

import com.wearedevs.someclicker.mod.Mod;

public class MyNewMod extends Mod {
    public MyNewMod() {
        //Code To Run When Mod is Loaded.
    }

    public void preInit() {
        //Code to Run Before Loading the Save File.
    }

    public void postInit() {
        //Code to Run After Loading the Save File.
    }

    public String[] save() {
        //Save Your Mod Stuff.
        return null;
    }

    public void load(String[] savefile) {
        //Load Your Mod Stuff.
    }
}