I love the simplicity of this app, but not having any explanation as to the intended categories and their default colors makes it hard to add new items that are not in the default library.  I would like to use the built-in color conventions but I am presented with strange circles and patterns that don't mean anything to me as a new user.  

What good does it do me to assign a color to a new item if I don't know what those colors are supposed to mean?  It's basically making me pick a color at random.  If you just had a list of what the developers intended the colors to mean, the user could work with that convention and stay organized.

Come on guys, finish what you started here.