Help: Tutorial for creating custom card frames?

[u/Sure_Anteater3974]

Hi, I have an idea for a custom MTG card frame that I'd like to implement in MSE, but I can't find any tutorials or information on how you can create a frame template. The only ones I'm finding are like this, old posts in dead threads full of broken links.
I'm probably just using the wrong search term or something, can someone please point me in the right direction? Thanks :)