I have a range of data that a user will constantly update. There are
four columns:

ArrivalTime (Time)
Appointment or Walk-In (A or W)
Appointment Time (Time)
Wait Time (Calculation of Time)

The user will enter:
Arrival Time in (B2)
A or W in (C2)
Appointment Time (if C2 = "A") in (D2).
and so on in B3, C3, D3

What I want to do is in Column E, calculate the Wait time accordingly
when a user clicks a button.
If Appointment - WaitTime = Now - Appointment Time
If Walk-In - WaitTime = Now - Arrival Time

Now the user may enter multiple rows at one time and then click the
update button.

How do I have it run through the range and run the calculations?

Brendon