Quote:calculating salary details using method...how should I call it using parameters
Well, that will depend on exactly what parameters you define your method as requiring!
Presumably, you pass it the Basic Salary, and it "fills in the blanks" in your class.
If so, then it will have a signature like this:
public void CalculateNetPay(double basicSalary)
So you would call it passing either a constant value:
Or a variable containing the value:
if (!double.TryParse(stringContainingUserEnteredSalary, out basicPay))