How do I enter birthdays into the calendar?

I’m lost in birthday land. Birthdays appears on the Calendar left pane, but birthdays cannot be entered there. I entered a birthday on the Contact list, and that seems to stick. The Contact list has numerous col. headings. Birthdays is scrolled far to the right. 1. is Contacts the correct place to enter birthdays? 2. Can I eliminate unused columns on the Contact’s list? Please and Thanks.

you can save birthdays inside the contact items or make a separate calendar for birthdays as you wish. I assume the default Birthday calendar is generated automatically (is this a Gmail account?) and those might be automatically synchronized there either from that accounts contact (or G+ if its a gmail account). Either way, this is probably caused by the server/mail/calendar provider setting.
As for the Columns, if you right-click the top row of the columns, you should be able to choose Columns configurations and set the order and which columns to display.