How do I customize banner width on this free theme?

How do I customize banner width on this free theme?

Here's is the link to my client's site:
http://contentchilly.com/
I opened editor in Wordpress and found only one slider related PHP. I do not know PHP but have an idea. So I found this file named "tc_voila_slider.php" and found that it had 3 lines like :
 <img width="1170" height="500" src="<?php echo TC_BASE_URL ?>inc/img/colonnes.jpg" class="slide wp-post-image" alt="<?php _e( 'Create beautiful sliders','customizr') ?>">
In all three lines, I changed the width to 500 and height to 200..but its not showing any change. How do I modify the widths and heights of my banner on slider? Its just stretching my banner images. Also I want to move the slider up a bit..there's a lot of space empty and below the sliders, there are 3 circles that I want to show users on home page so they don't have to scroll down. How do I get rid of extra spaces?
Please help. Thanks
edit..
Also, I put this code in style.css after inspecting the images in firebug..its no use either.
.slide .wp-post-image
{
width=200px;
height=200px;
}