Just got my Kobo Libra Colour

Hey all, fairly new to this, I just got my Kobo Libra Colour and pen since I will also be using it to read music books and it's helpful for annotations.

Obviously books but also comics and some manga.

Do you have any other tips as a brand-new user? I've seen some things about Kepubs, Calibre or other "readers" but not sure what that's about