> = And < = cannot be applied to operands of type string and string

The error is telling you exactly what the problem is. Basically, you have two string values here; one in lbltime.Text and the other in dwldetime. Now, I have no idea what type you expect in here so I'm going to assume for the purposes of this example that they are both meant to be numeric, which means that you are going to have to convert them into an appropriate numeric type. Now, suppose that these are both numbers, then you are going to want to use TryParse (a much better choice than using something like int.Parse or Convert.ToInt32 because it copes with rubbish values) to convert the inputs and perform the calculations on the returned values. Something like this would be appropriate:

int inputTime;
if (int.TryParse(lbltime.Text, out inputTime))
{
  int comparisonTime;
  if (int.TryParse(dwldetime, out comparisonTime))
  {
    if (inputTime >= comparisonTime && inputTime <= comparisonTime)
    {
      // ....
    }
  }
}

Please note that reading compiler error messages is a valuable skill. This one should be an easy one to understand for anyone who has been coding for any period of time.