I would do it like that:
string input = Console.ReadLine();
string[] words = input.Split(' ');
for(int i = words.length; i > 0; i--)
Console.Write(words[i-1] + " ");
Console.WriteLine();
Thats as basic as it can be, not a very elegant way to do it however.
By the way, there is no "print" in C# :)