Theme/extension not showing in extension window

I am trying to teach myself how to make a theme for FGU. All of my previous theme experience has been in HTML/PHP and I am completely unfamiliar with XML--though some of my experience seems to be translational. I am using the "Light" theme to learn from (5E). I made a copy of it and added a _2 to the end of the file/folder name just to keep it separate.

I went into the graphics_fonts.xml file and removed all instances of font shadowing. To me, it makes it harder to read and I wanted to start with something that I thought would be simple. I saved that file then opened the extension.xml file and changed the name of the theme. See this image: Attachment 41208

I then re-zipped, changed the file extension back to .ext, and uploaded the change. Attachment 41209

However, when I reload FGU, the extension is not visible as a selection in the load extension window. I'm sure I'm doing something wrong that's very simple, but I can't figure it out.

Also, and I apologize if this is a dumb question, but in looking through this theme extension, I'm not seeing anything like a layout--something that indicates this graphic goes here, for instance. What I'm ultimately wanting to is change the sidebar to a single column of text links, similar to Damned's Strahd theme or possibly relocating the sidebar to a top bar. Can anyone direct me where to look for that?

Thanks!

Dont package up the root folder - include all subfolders and all contents but not the top level folder.
Make usre you only use straight zip compression - nothing else.

desktop_library.lua in the Strahd theme.

Yep, that did it, was zipping at root level. Thanks!

Appreciate the info on the LUA page. That will help me considerably.