[DatePicker] change onClick (day) and day css

[DatePicker] change onClick (day) and day css

Hi all, I want to use jQuery UI DatePicker to show some events of my agenda.

This is my ideas:

I want show a busy day ( more than 4 events ) with red background colour ( on the day cell ).
When I have 2 events in the day green colour of the cell's background and go on.

Second question is: if in the day cell there are some events I want to make the cell clickable and redirect ( on click ) the user to a page.

Is there a way to do that? Thank you very much, Emanuele.