For those who are unfamiliar with using Adobe Extension Builder this tutorial should give a quick introduction on how to get started.
https://www.youtube.com/watch?v=e-_PGTWmbn4
Create a window / GUI / panel fast using HTML in After Effects
Moderator: Paul Tuersley
For Expression Tutorials:
https://www.youtube.com/c/CodingAfterEffects
https://www.youtube.com/c/CodingAfterEffects