How do I add a second birthday field just like the default one that is already there.  I can create the field, but I want a drop down arrow (combobox?) to display the calendar.  Is this possible?  How do I go about doing it

Additionally, I am adding a birthday field on a custom form.  I would like to add this to the details page on the standard contact form.  But, when I open the contact form, the only 'editable' pages are the general and blank tabs.  I can't place anything on the details page.  I want to put all my birthdays on one page