Help needed with SINGLE POST TEMPLATE

I’d be very pleased if one of you guys could help me.

I’ve managed to create pages and a page template that works correctly. I’ve also created categories and there are a couple of posts in each of them. Now I’d like to include all the posts from a certain category to the certain page. Is it okay to do that with query_posts('category_name=X'); ?

This is my problem:

I’d like to have each post shown in a box with a border and a background-image. I know how to create the box with css but what I DON’T know is how to set every single post appear in that box. I’ve been trying to create single post templates and also used a plugin with which I can define certain templates to show with certain posts, but they either ain’t working properly or I’m using them in a somehow wrong way. To sum up, all the posts in a certain category should be shown at the same time on a given page, each post inside a box defined in css. How to do that? Answers very much appreciated. 🙂 thanks!