Hi evilkitten,
Can you kindly clarify if you already have Little Reader? This software is required for all the downloads you can find in the "Little Reader Library" section of the Forum, in the same way that Little Math is required for downloads in the "Little Math Library" section.
If you have LR already but can't import what you've just downloaded into your software (e.g., this "dinosaur.cat" file), please make sure that you have downloaded the file completely, and once the download is finished try right-clicking on the file and choose "Open With > BrillKids Little Reader." This way you can manually make LR open this file and import it into your LR lesson library.
If you don't have LR yet, perhaps you can try downloading files in the "Free Downloads" section -- here you can find lots of PowerPoint presentations, printable flash cards, activity sheets, or eBooks in English and Foreign Languages.
I hope this helps!