This example will show you how to read user input from the console application in C#.NET

double x, y;
Console.WriteLine("Enter your x value:");
if (double.TryParse(Console.ReadLine(), out x)) {
  y = x * Math.PI;
  Console.WriteLine("y={0}", y); 
} else {
  //illegal input

You can use the ReadLine method to get a value from your user input

The ReadLine method that helps you read the next line of characters from the standard input stream