Twitter Bootstrap 3: how to use media queries?

These are the values from Bootstrap3:

@media only screen and (min-width:960px){

        /* styles for browsers larger than 960px; */

    }

    @media only screen and (min-width:1440px){

        /* styles for browsers larger than 1440px; */

    }

    @media only screen and (min-width:2000px){

        /* for sumo sized (mac) screens */

    }

    @media only screen and (max-device-width:480px){

       /* styles for mobile browsers smaller than 480px; (iPhone) */

    }

    @media only screen and (device-width:768px){

       /* default iPad screens */

    }

    /* different techniques for iPad screening */

    @media only screen and (min-device-width: 481px) and (max-device-width: 1024px) and (orientation:portrait) {

      /* For portrait layouts only */

    }

    @media only screen and (min-device-width: 481px) and (max-device-width: 1024px) and (orientation:landscape) {

      /* For landscape layouts only */

    }