On duty, it took to highlight some days in fullcalendar color. I decided to finish it a little. What did you do: In the parameters added custom - collection of days. For each day, you can stick the css class and callback function, which will be executed when you click.
* This source code was highlighted with Source Code Highlighter .
Maybe someone will be useful. See archive / demos / default.html ')
PS Do not forget that new Date (..) Month must be specified starting from 0. i.e. January is 0. This can be misleading if you forget.