Posts on a Static Page via Category

I did use the search to find the specific answers to my question but couldn’t find any to my satisfaction so far. I apologize in advance for adding yet another post on posts on a page topic.

I’m using the Posts on a Page template found at http://codex.wordpress.org/Pages#A_Page_of_Posts but my question is where do I modify the category id and page id within the code provided? I couldn’t find the answer or if I overlooked something here. I tried to use Custom Field using the page_category and categoryname in value field, but it’s not working. I’m not sure how to set up the custom field on the page I’m using.

I did make a new template based on that code and used this template for the specific static page I created but not sure how to display posts from specific category.

Thanks for your help in advance.