Wordpress custom categories in FrontPage

Hello. I have a wordpress theme with a custom Front Page already created by the theme with a little Slider and then articles.
Because is only a simple custom front page without options in the Theme Menu, i can't select what posts are shown in the Slider.
I just want to show articles from a specific category in that Slider, because now are the latest articles.
I tried to find a workaround with the following code but didn't succeed:
and also with that
But still didn't managed to make a change.

The custom home page code is: http://pastebin.com/MMZFNKVy
The website where you can see an example of the theme is : http://leadrights.com

Thanks a lot guys.

I use a plugin called Related Posts Slider.
http://wordpress.org/plugins/related-posts-slider/
You can choose your post category with that dude.

Hi, thanks for your suggestion but i need to keep the theme with its original slider. I need to modify the actual code of the custom homepage. Thanks.
//Later edit:
Resolved it after trying more things from here http://codex.wordpress.org/Class_Reference/WP_Query . Thanks.