Highlighting Current Page in menu….

Can somebody help me out with this?
I am using Egesto as my theme, and automatically it came with a script that would highlight the current page in the top menu.
i think the code is one of these lines..

‘<?php if ( has_nav_menu( ‘main-menu’ ) ) { ?>
<?php wp_nav_menu( array( ‘theme_location’ => ‘main-menu’, ‘menu_class’ => ‘mainnav superfish’ ) ); ?> ‘

Anyways, I wanted to make a customized drop down menu. So I removed that top line of code, and put in a line of code to refer to a plugin I downloaded. In the plugin is the HTML for the customized drop down menu…however, the current page is no longer highlighted in the menu..

I tried looking this up, seeing something about CSS and giving each link an id, and putting the id in the body tag of each page…HOWEVER, i can not find a body tag for each of my pages, as it is only in the HEADER of the overall website..

Can anyone help me with this?

THANK YOU!