GitHub coding setup

GitHub coding setup

I am new to GitHub. I managed to install GitHub for Windows and created a
github repository. I'm a PHP developer and this is my current situation
before GitHub.
Currently, all of my work go to C:\xampp\Dropbox\* ("htdocs"). Everything
I code is in there with each application under its own subdirectory.
Whenever I need to update the production server, I FTP our production
server and upload the necessary files. This is good when I am working
alone but working with other developers would be hard because we need to
know who edited which, when what was edited, etc.
Could you help explain how I can maintain my codes using GitHub? I suppose
that I shouldn't make the entire htdocs as a local repository. I access my
codes via http://localhost/ when testing it locally. Since I develop web
applications using PHP, code changes regularly. We don't compile codes and
I was used to simply saving all the files and letting Dropbox save all the
versions I made.
It's a bit confusing what to do next since the GitHub for Windows
application created local repositories in
C:\Users\Admin\Documents\GitHub\test-app folder. Should I edit the code in
htdocs and ALSO edit the code in My Documents\GitHub? Then also "push" the
update to GitHub AND also update our production server via FTP?
So, to summarize, from the primitive perspective of web development, what
steps must be changed so that I can enjoy the benefits of using version
control systems such as GitHub?
Thank you!