6. Troubleshooting: in progress...

I only see the Scripts/Ports section
Open sections.cfg
Check your rom paths, make sure they are pointing to your roms and have a "/" at the end
Check that the extension of your roms is listed in the section config (for instance, snes might have .smc but you may have .sfc roms)

I have changed the extension but my roms still don't show up
Make sure you are not putting spaces between commas (".sfc,smc", good, ".smc, .sfc", bad)

I see my roms but, when launching them, nothing happens and I get sent back to the menu
Check that both your emulator folder for that section as well as the name of the emulator executable are correct in the corresponding section definition within the section group file.

MAME doesn't launch my roms after picking them in SimpleMenu
If you are using MAME4All, it won't accept roms as command line parameter and will force you to use its own rom picker.