using theme for Fullcalendar

I saw few themes demo in fullcalendar download package. In my application i have different calendars like Leave calendar , travel calendar and events calendar. I want to use different theme for each calendar. i set

theme: true

in my coding but exactly i dont know how to use the particular theme for that calendar. For ex, i want to use bootstrap 3 - Lumen theme for event calendar, where to get and include that css file. Or i have to make my own css theme file.

$(document).ready(function() {  
    $('#ConfCalendarBlock').fullCalendar({      
        header: {
            left: 'prev,next today',
            center: 'title',
            right: 'month,listMonth'
        },

        theme: true,    
        themeSystem:'bootstrap3',        
        height:400,
        editable: true, 
        displayEventTime: false,        

        events: modJs.getConfJsonUrl(),     

        loading: function(bool) {
            if (bool) $('#loadingConfCalendarBlock').show();
            else $('#loadingConfCalendarBlock').hide();
        },

        dayClick: function (date, jsEvent, view) {

                modJs.getdayclick(date.format());               
        },          
        eventClick: function(calEvent, jsEvent, view) { 
            modJs.geteventclick(calEvent.id);
        },   

    }); 
});

All my link files is included in header.php file

 <link href="<?=BASE_URL?>themecss/bootstrap.min.css" rel="stylesheet">
    <script type="text/javascript" src="<?=BASE_URL?>js/jquery2.0.2.min.js"></script>
        <script type="text/javascript" src="<?=BASE_URL?>js/jquery-ui.js"></script>
        <!--fullcalendar-->

    <link href="<?=BASE_URL?>js/fullcalendar/fullcalendar.css" rel="stylesheet">
    <link href="<?=BASE_URL?>js/fullcalendar/fullcalendar.print.css" rel="stylesheet" media="print">
    <script src="<?=BASE_URL?>js/fullcalendar/lib/moment.min.js"></script>
    <script src="<?=BASE_URL?>js/fullcalendar/fullcalendar.min.js"></script>