Archive Help

First I am using this code in my sidebar to provide the user with a dropdown menu to view archived content based on month.

<select name="archive-dropdown" onChange='document.location.href=this.options[this.selectedIndex].value;'>
  <option value=""><?php echo attribute_escape(__('Select Month')); ?></option>
  <?php wp_get_archives('type=monthly&format=option&show_post_count=1'); ?> </select>

When the month is selected it takes the user to a page where I was able to spec the template by uploading an archive.php file. I am in the process of making my own template, so some of the files are new to me.

When the user selects month it goes to the page and it shows all posts, I would like to only show certain categories on this archive.php or exclude some, whichever is better. I only want to show categories “news’ and “reports”, but I have few other options for categories and I do not want them archived like that.

Any help! Thanks a ton.