Accessing another computer's files accross my home private network

Back in the days of Windows 3.1 or 95, I kind of forget, I started simply setting the exact same user name and password on each of my home computers, then setting each computer's drive to be shared. I strongly doubt this is the correct way, and now with one of my computers running Windows 10 which does not even allow me to use a common user name but forces an email address, I guess the days of doing things wrong need to be gone.

Can anyone direct me to a good resource that VERY simply will show me step by step how to set each computer's settings so I can access the computers, drives, directories and files? And by "access" I should state I mean Full Access -Read, Write, Create, Delete and anything else one might wish to do?

Thank-you very much!

THANK-YOU (and yes, in my head I am shouting my greatest "thanks" for your help!). I am off to learn from each of the resources you provided and will advise.

Once again, THANK-YOU!!!

OK, I have learned some, noted the tutorials, and am looking to learn more, and am here most embarrassed, but I think I best post my blunder so others might not trip over their own feet as I have.

Turns out I was blocking myself on the firewall of the computer I could not reach. I have little idea of just how I messed up, for another computer running W7 on the network has no problem seeing all the files on the other computer, but I have sent the writer of Windows Firewall Control a brief note asking if he would be so kind as to unscrew me.

Thank-you for trying to help me; I have learned from those links and look forward to learning more.

Best regards,
Bruce