Is there a way to show / hide certain months or months older than....?
In WP or in the theme?
control over months shown in Archive widget4 posts from 3 voices
Assuming you mean the Sidebar News widget, you can adjust the query parameters by editing this line:
$additional_loop = new WP_Query("cat=".$cat."&posts_per_page=".$count);
The Query Posts article in the WordPress codex http://codex.wordpress.org/Function_Reference/query_posts (scroll down to Time Parameters) should give you the information you need depending on the restrictions you require.
I'm sorry for my innexperience. Which files should I look for?
You need to edit sidebar_news.php located under newscast > framework > theme_widgets > sidebar_news.php
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