Hello, it is possible to do capturing the scroll event and check if the scrollTop is larger than the size you want.
 I would use the following code
$(function(){
    var jElement = $('.element');
    $(window).scroll(function(){
        if ( $(this).scrollTop() > 300 ){
            jElement.css({
                'position':'fixed',
                'top':'300px'
            });
        }else{
            jElement.css({
                'position':'relative',
                'top':'auto'
            });
        }
    });
});
Where we save the variable of our element with the jElement, we check when the user scrolls on the page with $(window).scroll(); and check if the scroll is larger than 300 (you can switch to any value you want) with $(this).scrollTop(); see an example working here:
http://jsfiddle.net/Wagner/cwzVQ/embedded/result/
							
							
						 
Exactly this page uses a plugin: http://bigspotteddog.github.io/ScrollToFixed/ - but this is not difficult to do. If you put your code you will get a more personalized answer.
– Sergio
Cool Sergio.. I’ll test it. Thank you!
– Maicon