Screenwriting : Long Time Watcher, First Time Writer by Sari Eliza

As an LTWFTW, I've written some good narrations and dialogues, but I'm starting to realize I'm not writing proper scripts (courier font, size 12, etc.). It'd be easier to convince museum curators with the amateur setup scripts than the real media pros. Therefore, for the logline I posted here on Stage 32, I'm now doing my first Official screenwriting! Set up the formattings well, getting the feel with the first 5 pages--

WikiHow was perfectly informative, though it's just the basics. That's why I'm here on this website! For instance, the story I have is challenging against my strength of dialogues. I'd written many stories before that, as my high school graphic arts teacher says, makes me capable of doing voice direction. But I don't want my animal characters to be chatty. I'm taking an approach that doesn't need any speech for interactive communication.

How do I write dialogue for a creature that doesn't talk?