It has been too long since I looked at a tutorial, for me to suggest a stand-alone, independent, tutorial with confidence. A lot of the information you are asking about is specific to particular board fabricators, so you should start with the website for the board house you will use.
The netlist can almost certainly be ignored. In fact, starting with KiCAD 5.0.x, the netlist is an artifact left over from outdated ways of doing things in KiCAD.
You generate Gerber files using the selections “File” > “Plot” from the top menu bar. (This is also the menu you use to create *.PDF, postscript, or *.DXF files for documentation, collaboration, etc.) The array of options in the “Plot” menu looks intimidating, but the default selections are acceptable for 95% or more of all board fabricators. Circuit board fabrication has matured and standardized quite a bit over the last 15 - 20 years, and many fabricators are much more tolerant about the fabrication files than they were in the “good old days” (previously known as “these difficult times”). Some of them will identify and correct common mistakes without comment - occasionally even “mistakes” that aren’t “mistakes”, and should NOT have been “corrected”.
A recent thread that discussed the same question you are asking is at " Tutorials on prep’ing PCB for board house? ". (You DID use the “Search” feature to look for similar topics before you posted yours, didn’t you? 
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There are additional considerations if your boards will be assembled by an assembly shop. These requirements are much more individualized than the constraints for producing bare boards, so you will have to contact the assembly shop yourself and discuss their requirements.
Dale