There are several tutorials, but I also have a few github that help beginners get setup. (Also a channel called Wituz on youtube that has a PSX dev tutorial series - but he uses very old software to compile the games).
Basically the steps to get to iso:
1) Setup the development environment (SDK + compiler + make)
2) Compile the ps-exe (most emulators can run this - but of course it does not contain audio CD)
3) Use a tool such as mkpsxiso to make the CD image (if necessary)
A good place to get you started:
http://psx.arthus.net/starting.html