Validate Date

Question

I have a text box on a web form where a user will input a Discharge Date...The date MUST be entered in this format MM/DD/YYYY what C# code would validate that the entry is input in that format, and if not show an error?  Something like:
ButtonFinish_Click()
{
//check to see if the date is correct format
try
{
//how to check?
//if valid Response.Redirect -- Go to next page
}
catch
{
Error.Text = "Dates must be entered in a MM/DD/YYYY Format.  Please check the entry and try again."