for int for int arrOne Length if arrOne max max arrOne maxIndex

 for (int i = 0; i < 3;i++)
            {
                for (int j = i; j < arrOne.Length; j++)
                {
                    if (arrOne[j] > max)
                    {
                        max = arrOne[j];
                        maxIndex=j;
                    } 
                }