well as far as windows 3.1 goes... you can't basicaly there is no file sharing with 3.1, but WFWG 3.11 does have file sharing so i suggest upgrading to that before doing network stuff. in windows 98 to enable file sharing (if it hasen't been already) right click on the network neighborhood icon and then select properties, on the very first page it shows there is a button that says file and print sharing, click on that, now check the box that says "i want to give other access to my files" then click ok, now its gonna wanna restart the computer so let it do that, now to share a folder right click on it and select sharing, then check the box that says "share as" and give it a name and a password if you like, the rest is pretty self explainintory, now on your 3.1 computer (if your still using 3.1 at thi time and have all the drivers loaded to allow networking in 3.1) open file manager, on the file menu click "disk" then click "connect network drive" then type in the path to you 98 pc, example:
if your 98 pc's name is "server" and the name for the folder you shared was "share" you'd type this in the path box
\\server\share\
if you don't know the name of your 98 pc then look in the network neighboorhood on your 98 pc, it should list it there. ok now if you've done all this and it doesn't work then there are more things to setup, but a great place to get information on how to set it up is www.wown.com thats where i learned how to setup 3.1 on a network, but i strongly recomend WFWG because its easier to setup.