how to make a template for a specific category

I need to make a custom category template for a category with id=5. My theme doesn’t have category templates. How do I make posts appear in the category page? my theme makes it possible for posts that appear on the page to be viewed as a list or as a grid. I need the posts in the category to have that option as well.

this is the code for making the list or grid option I think.

<ul id="index-style">
						<li id="index-style-thumbnails"><a href="void(0);">"><span class="icon-list">?</span></a>
						<li id="index-style-grid"><a href="void(0);">"><span class="icon-grid">?</span></a>

Also if someone can tell me what the following code does it’ll be a big help. They are located above and below the list or grid style code in the index.php.

above:

<!-- index -->
			<div id="index" class="content index-<?php if ( of_get_option('style_selector') ) { echo of_get_option('index_layout'); } else { echo 'thumbnails'; } ?><?php if ( of_get_option('full_posts', 1) ) { echo ' full'; }  ?>">

				<?php if ( of_get_option('style_selector') ) { ?>

below:

<?php } else { ?>
					<script>
						jQuery(function($) {
							$.cookie('conduit_style', 'null');
						});
					</script>
				<?php } ?>

[please follow the forum guidelines when posting code – some of the code above is already partly corrupted]