How to write Libre Office Calc Macro for update and add or less one day each

I want to update current date in a Libre Office Calc worksheet cell and add or less one day each in same cell using push button and macro. Please help me.

It is not exactly clear what you wish but here is a macro to increase the date in cell A1 by one day. Assign this to the Execute Action event of a push button. Duplicate the macro with the one line changed to decrease the date & attach to second push button.

Sub IncDate
    oSheet=ThisComponent.CurrentController.ActiveSheet
    Cell = oSheet.GetCellRangeByName("A1")
    myDate = Cell.getString
    currMonth = Month(myDate)
    currDay = Day(myDate)
    currYear = Year(myDate)
    serialDate = DateSerial( currYear, currMonth, currDay )
    'Replace next line with serialDate = serialDate-1  to decrease date
    serialDate = serialDate+1
    Cell.setString(serialDate) 
End Sub

It works… Thank you