Some fun with refactoring

Let's say you have an application in one huge file.

    using System;
    using System.Collections.Generic;
    using System.Linq;
    namespace MyNameSpace 
    { 
        class Doer 
        { 
            private List<ItemClass> _allItems = new List<ItemClass>(); 
            private List<ItemRuleClass> _allItemRules = new List<ItemRuleClass>(); 
            
            public Doer(string myParameter) 
            {
                LoadData(myParameter);
                //Loads the two List<T> shown above. Out of scope of this project 
                MainProcess();
            }
            public void MainProcess() 
            {
            }
            //... 
        }
    }

How would you refactor it?