A bit of a double post, but not sure if you get the notification that I replied to another question here. So if you still are having problems, press the little "settings" icon in the bottom right of the palette menu. From there select the brushes you installed.
Sorry, but as a beginner I don't understand this. You say (in very small font!) that an imported brush has to be in .png format. Everywhere else I read that it is possible to import Photoshop brushes in .abr format. On the internet many brushes are offered in .abr format. But I can not import them. After downloading the .abr file and then importing them via the brushes palette menu, nothing happens. Unfortunately, the manual says nothing about this matter. Your little tutorial doesn't help me since I cannot find brushes in .png format. Where should I look?