Check out example codes for "c# warning CS0108". It will help you in understanding the concepts better.

Code Example 1

//warning CS0108
class Bicycle : Vehicle					//Subclass
  {
    public override void SpeedUp()		//Add 'override'
    {
      Speed += 5;
    }
  }
  
//error CS0506
class Vehicle							//Superclass
  {
    public virtual void SpeedUp()		//Add 'virtual'
      {
        Speed += 5;
      }
  }

Learn ReactJs, React Native from akashmittal.com