how to input a pop up to advise me about my deadline?

Assuming that you have your deadlines for various events in one column:
1. Select the first cell containing a deadline (assume A2)
2. Click on Format>Conditional formatting and select "Formula Is" in the leftmost dropdown window and enter this formula in the window that appears:
A2<=today()
3. Click on Format button and choose Pattern and select a color for the background of the cell and click OK.
4. Use the Format Painter tool button and copy the format to the other cells containing deadlines.

The result is that any cell with a deadline equal to or before today will be hi-lited in color you choose.

Another way if you want a Pop-up window is to put the following code in the "This Workbook" code module:

Private Sub Workbook_Open() 
If Date = DateValue("3/9/2005") Then MsgBox "Reminder: Do something" 
End Sub

Substitute your deadline date for "3/9/2005" in the code. and your own message for the text: "Reminder: Do something"

Thanks to Oaktree on another board for this code.