Beginning modules, procedures, and service programs.

I finally decided to move towards the 21st Century.  The whole idea of prototypes, modules, service programs, and ILE concepts has been a curiosity to me and avoided by me.  But no more.  I have been reading articles, looking at examples, and working with service programs.  It still bewilders me

May I say back what I think I have learned, with the idea that I probably got much of it wrong?  I am barely past Hello World, and much of what I read is targeted to a level somewhere above that. I need to get my basics right.   (I appreciate the patience and the talent here o Midrange.com)'

Typically  I have made a series of small programs to do the various activities needed for an application.  There would be a program to create the file(s) needed for the application, the program to edit those files,  program(s) to communicate the data to & from users, ancillary programs for F1-Help, F4-Prompt, etc., and the display files to go with all of that.

If I understand correctly, the programs and their display files would now become modules?   A service program would be written to combine those new modules?  There would be another service program for the wider-scope activities, like default values, message files, and communications applications.

At that point every thing starts to fall apart in my head.  So let me offer a simple situation and ask what pieces should I create for that situation:

NameFile, with name, street, city, state, zip, phone, and email. I need to create the file, edit the file (including a default for message file for language-to-use, dropdown (F4) on state, and an F1 key for system-wide Help defaulting to NameFile help).  I also want to provide F4 screens for name, city, & state so other applications can plug in dropdowns for valid name, city, & Sates for their own applications needing name & address info.