Text box validation not working

Question

Right now the code below tests for a blank text box. If it is blank it returns the error stated below the if statement. That works fine, but I also want it to check for wh

Answer 1

What about:

if (txtFirstName.Text.Contains(" "))
{
    txtFirstName.BackColor = System.Drawing.Color.Yellow;
    lblError.Text += "Please enter first name without blanks
";             
}