No problem; it looks like you just mixed up the installation process for the commands and the custom UI.
It seems you've already installed your commands, so just go for fixing the custom ui. I'll put the links in case you need them.

To install commands, follow the guide here:
https://moi3d.com/faq#Q:_How_do_I_install_a_plug-in_script.3F
For example, the edgeFlange.js and edgeFlange.htm files should go directly into the "commands" folder.

To install the custom UI, follow this instruction:
https://moi3d.com/forum/index.php?webtag=MOI&msg=6507.268

Take your time and try again. You'll see it's quite simple once you get the hang of it.