Where to install the calendar widget?

I have a blog that I use to communicate with my students and their parents. I want to put a calendar on the blog page. There are two kinds of events that I want to include on the calendar. There are events that effect ALL students (vacations, assemblies, etc), and there are some events that only effect the students in one class (I want to put their birthdays on the calendar but I only want each class to see the birthdays of the students that are in that class). Can this be done?