Books are downloaded into your "my documents/Downloads" folder.
If you're viewing books from trook itself, navigate to that folder and refresh it. If you're viewing books from one of the library applications, you'll likely need to "check for new content."
Feeds are bookmarked into your "my feeds" folder, which is accessible from your root menu. Please restart trook if needed, as there's a bug in rev45 that prevents this folder from showing up if you bookmark anything for the very first time. To restart Trook, long tap the settings icon, and pan-scroll down to the last item which says "stop application."
(More Information about this and other details is also in the Trook documentation
. You can also access updates, news and the same documentation from within trook -- rootmenu -> nookdevs -> trook.)