How do i convert Strings to Integers?

You could take that 1 step further with the following:

int iAge = 61;
int yearofbirth = DateTime.Now.Year - iAge ;
DateTime x = new DateTime(yearofbirth);
TimeSpan xx = DateTime.Now.Subtract(x);

The TimeSpan object with give you almost all of that information with doing all of those calculations and will be more accurate taking into considerations the correct number of days in each year.

Of course, thanks!
that would explain the large numbers i was getting! thanks

Thanks a bunch, it was the
  Convert.ToInt32(age);
I was confusing the Convert, with Console. Thanks though, much help for a beginner such as myself!

However, i can see 

  int.Parse(age);

being much more easy to remember.

Just to say - this is what I've come up with

            String name = "";
            String age = "";
           
            int end = 0;


            while (end == 0)
            {

            Console.WriteLine("Enter name:");
            name = Console.ReadLine();

            Console.WriteLine("Enter Age:");
            age = Console.ReadLine();

            int iage;
            bool isValid = int.TryParse(age, out iage);

            if (iage != 0)
            {
                Console.WriteLine("Hello " + name + ".");
                Console.WriteLine("You are " + iage + " years old");
                Console.WriteLine("You are " + (iage * 12) + " months old");
                Console.WriteLine("You are " + (iage * 12 * 52) + " weeks old");
                Console.WriteLine("You are " + (iage * 12 * 52 * 7) + " days old");
                Console.WriteLine("You are " + (iage * 12 * 52 * 7 * 24) + " hours old");
                Console.WriteLine("You are " + (iage * 12 * 52 * 7 * 24 * 60) + " minutes old");
                Console.WriteLine("You are " + (iage * 12 * 52 * 7 * 24 * 60 * 60) + " seconds old");
                end = 1;
                }
            else
            {
                Console.WriteLine("Please enter an integer e.g.) 9");
                }
            }
           
            Console.WriteLine("Press enter to exit.");
            Console.ReadLine();