Hi Monika,
Depends on what you are trying to edit. Typically, in Moodle plugins, editing and what can be seen, depends on the role of the person loading the page.
It helped me when I started trying to develop code for Moodle, to look at the code for some of the more simple plugins. I used the Journal plugin, as it has most things needed to help know what is needed for a new plugin.
I have been delayed looking at your code due to having eye surgery on Tuesday, but I can already see a couple of things you might want to consider doing.
There is no need to put your code in a zip file at github. I have git set up on my dev computer and use a visual git gui that keeps track of the files that are changed, and need to be sent to github. While developing a new plugin, each time I have got something new working, I push it to github, then make a new version branch. That way github is keeping track of everything for me.
I installed PHPdoc check and Code-checker, both of which help do things the right way for Moodle.
The biggest help for me came when I discovered the Moodle tutorial for plugin development.