I am a bit confused, so this question will probably reflect that,
I am using Joomla 1.5.21. I have some css code that creates a horizontal ruler with a background image and text. I want to add this special divider to only one page in my website. It will act as a nice divider between categories. I don't know if I should just add the new css to the current template css, or create a new css page and attach it to my site.
I am just starting to work with joomla. I really am not sure how to find and access the template that contains the css for this website. Or If I should create a new css page, how to do that.
Any advice - or a tutorial that would guide me with this project?
It really depends on what type of content you are displaying it on. For a category list I would think it's something that has to be included in the template. If it was an article you could use a custom HTML module and include it in the article body.
You can give your page (if it's a menu-item) a specific class in the 'Page Display' section when you are under menu.
In this way you can style that specific page in your css to your needs.