1. Log out from Drupal (or use another browser) to browse around your site
as the anonymous user. Ensure that static files are indeed being
generated into the Boost cache directory you specified above (#4); and if
you opt to use gzip, likewise check gzipped files are being generated in
the directory you specified for this.
The Administer > Performance > Boost settings page shows how many pages
are cached by Boost.
2. Check the Drupal status page [Administer > Reports > Status report]
for any errors or notices.
3. To check whether you have a cached or dynamic version of a page,
look at the very end of the page's HTML source. You have the cached
version if the last line looks like this:
<--Page cached by Boost @ 2009-08-11 06:19:58,expires @ 2009-08-11 09:19:58-->