Limit Categories in Twenty Eleven's Showcase Template

Hi!

I just started using WP as a CMS since I watched https://en.blog.wordpress.com/2011/08/19/growth-of-wordpress/ and got interested.

I use WP3.2.1 and Twenty Eleven as Theme. The migration went very well but for one thing: how do I display articles of a certain category on a static page?

I have a static page about travel, a static page about Android and a “normal” Blog. I would like to have the blog articles that I put in the category “travel” displayed on the corresponding static page and the same for Android.
It seems to me that the Showcase Template is the way to go, but I haven’t found any way to limit the stream to a certain category (or to change the header of the stream for that matter).

Is there a plug-in to solve this or at least some how-to on code manipulation? I am a PhD student of computer science, however, my field of expertise is assembly code verification of embedded systems not CSS or PHP. So be gentle ??

Currently, I use static links to the articles, which is rather ugly. Thanks for your time and help.