My b2evolution Version: 1.9.x

Heej guys,

I have a (pretty basic) question, which I can't seem to find to answer to. I have a blog on my website, and now I want to add a second one for another subject. My main blog is located on the root level, so if you go to http://www.nwn-music.com it is displayed immediately. The second blog should be placed in http://www.nwn-music.com/composition. I already created the blog in my control panel, and the link to it is showed on my main page, but it will give an 404 error when clicked upon.
Pretty logical, since there is no file in the composition map. Now B2 says
"With trailing slash. By default, leave this field empty. If you want to use a subfolder, you must handle it accordingly on the Webserver (e-g: create a subfolder + stub file or use mod_rewrite)."
Fine by me, but does someone know how to create a stub file, which data it should hold, or how to use mod_rewrite?

Thanks in advance!
Erik