HOW DO I NETWORK 2 COMPUTERS TOGETHER?

To whom it may concern:
This is probably an easy question for many members here, but I need help in setting up 2 computers for a home network. My mom would like to network my computer and hers together at home so we can access each others files. Please tell me everything that would be involved and how I would go about setting it up.. THANK YOU VERY MUCH!!

P. J. Peterson