Get a piece of papaer and a pencil and go through the loop and work out carefully where it starts and stops, so you can get it to stop when you enter stop.
Enter Employee Name: Campbell
Enter the employee pay rate:12.34
Enter the hours worked this week: 42.5
Employee Name is Campbell
Weekly pay Amount is $524.45
Enter Employee Name: stop
Enter the employee pay rate:99
Enter the hours worked this week: 12
Employee Name is stop
Weekly pay Amount is $1188.00
Hint: there is an awkward syntax which allows you to enter a name and check its equality to stop, all inside the () after while. If you search long enough for payroll classes, you might find somebody else on the Ranch who used that syntax.