Click the stuff basically. The accessories don't open menus, though, they cycle. Click the red X under fur to close it's tabs, because they all overlap each other. And click the stage to change the colour of the BG, so you can see your cat properly.
I'll add more stuff even after I have all the basic stuff, but I'll still only use realistic colours and markings. Sorry XD Inspired by https://scratch.mit.edu/projects/219371949/