Get cnet.device from Aminet and check if you have one of the listed cards. Then get Miami or AmiTCP or Genesis and configure the TCP/IP network. Get Samba to let PCs access your Amiga's drives, get SMB-Handler or SMB-Connect or smbfs to access your PC's drives from the Amiga. Samba needs lots of CPU power, without a 68060 you should not try it.
http://uk.aminet.net/aminetbin/find?cnetdeviceBye,
Thomas