Hi Roshan Kamble
Are you using the CaendarDB that Richard created?
If you are you do not need a pop-up form. Just run your calendar form but add a field to your listbox and your table of course [Birthday] Iterate through your listboxes if Birthday is Yes then change the background colour of your listbox. If you would like the code let me know and I'll post it.
Richard taught us how to grey out {not current month} it's just an extension of that. The trick is Interating through your listboxes. I set mine up Yellow background if there is a record, Green Header for School Holidays, Purple Header for Public Holidays, Red Background for Birthdays. Works a treat. I have Next Month Buttons ect. You just have to make sure you repaint all your listboxes when you change months or years ect.
PS I populated my Listboxes with a SQL statement. If you do not live in USA you will need to convert on the right side of your WHERE clause = USDate format for it to work 28/12/2011 has to be 12/28/2011. I do not know why. It does does. Probably because it's not an Australia or British product. Have Fun  
Best wishes Alan Hill