Documentation recommendation ?

I am trying to understand the steps that occur when a browser sends a URI to a CI app. There is some interaction between .htaccess, xampp.conf, config.cfg, and all the other files in the config directory. I need to move my app to gc app engine where there is no ht.access nor xampp.confd  but there is an app.yaml which has its own rules.

I can't seem to find an explanation of the steps involved. Can anyone point to an easy to understand paper or documentation?

Thx

proof that an old dog can learn new tricks