You can view your calendar by day, week, month, or year. Use the navigation panel at the top of your calendar to change views. You can also use the pull-down navigation tab next to "Calendar" (between "Addresses" and "Notepad") to change the views as well as access other features of Yahoo! Calendar.

In Preferences, you can set which view is displayed each time you open the calendar. Just select day, week, month, or year under "Default View" in the Preferences section.

If you schedule an event outside the hours displayed in the day view, Yahoo! Calendar will add a new line to your day view for that time. There is no need to shift to a 24-hour view.