The task is very interesting :-)

Here is my solution - I wrote a lot of explanations in the comments - so you can read and understand how to solve it...

using System;
class FibonacciNumbers
{
static void Main()
{
Console.WriteLine("Please enter your number:");
int n = int.Parse(Console.ReadLine());
if (n == 0)
{
Console.WriteLine("Invalid input!");
return;//we use return to terminate the program if "n" is 0
}
else if (n == 1)
{
Console.WriteLine(0);
return;//we use return to terminate the program if "n" is 1
}
int x1 = 0;
int x2 = 1;
Console.Write("{0} {1} ", x1, x2);//we print the first 2 numbers of the Fibonacci sequence
for (int i = 2; i < n; i++)//we do the calculation for the numbers ABOVE 2
{
int x3 = x1 + x2;
Console.Write("{0} ", x3);//we use Console.Write INSTEAD OF Console.WriteLine - to glue the above Console.Write - the start of the Fibonacci
x1 = x2;
x2 = x3;
}
Console.WriteLine();
}
}