It's pretty easy: Click on a topic (that's the white words in the blue squares) to open the respective article and re-click the topic, to close it again.
Now with the red squares it's pretty much the same—click to open, click to close.
If you open "archive" or "tags" and click on a date or a tag, you'll find a filter applied (in a pink box) which you can remove by clicking—as we are accustomed to—on the 'x' in the upper right.
Allright, everything else shoud be even more self-explaining.
ATTENTION: If you don't see no thing on the left side, that means no blue squares and somesuch, it may be up to your browser (if you use Internet Explorer older than version 8 it definitely is). You can visit a more basic version of the page, that should work here.
