multiple blogs, one domain

hello – i have a site with 6 sub dirs, 6 different topics. as of now, i have the site setup just as a site, no blog. how would i go about setting up a blog subfolder? i have my site set to a static page, if i switch it back, all my page content from my sub dirs appear on my main page…its odd.

or is there a way to convert each sub dir to a blog?

thanks in advance.