Abstract Factory pattern in simple terms

Just tried out abstract factory pattern... One of my colleague had issues coming up with the pattern.. Just helped him with the sample below;

Invocation point:

var obj = FactoryManager.GetFactory(1);

Implementation:

namespace ConsoleApplication2
{
    internal class RootDO
    {

    }

    internal sealed class SubDO1 : RootDO
    {

    }

    internal sealed class SubDO2 : RootDO
    {

    }

    internal abstract class RootClass<T> where T: RootDO ,new ()
    {

    }

    internal sealed class SubClass1<T> : RootClass<T> where T: RootDO,new ()
    {

    }

    internal sealed class SubClass2<T> : RootClass<T> where T: RootDO, new ()
    {

    }
    internal interface IFactory<S, T>
    {
         S GetObject();
    }

    internal class SubClass1Factory : IFactory<SubClass1<SubDO1>,SubDO1>
    {
        public SubClass1<SubDO1> GetObject()
        {
            return new SubClass1<SubDO1>();
        }

        internal static SubClass1<SubDO1> GetFactory()
        {
            SubClass1Factory s = new SubClass1Factory();
            return s.GetObject();
        }
    }

    public class FactoryManager
    {
        public static object GetFactory(int type)
        {
            return SubClass1Factory.GetFactory();
        }
    }
}