Hi,
hopefully this helps. Open Miami and right click, and select Import settings form MiamiInit. If MiamiInit figured everything out, you should be able to go online at this point (don't know if you have already done that).
You could also set it up manually. Press hardware, press new, press ethernet, type in a name, find the drive, press SANA-II parameters, press Query device. If something pops up, Miami has found your ethernet card.
Now press interfaces, press new, select ethernet and internet, select your ethernet card you just set up, and now just type the ip adress and stuff into the fields, or set it to DHCP. Now click online in the interfaces menu. Hopefully you will now be online.
If this is not what you wanted (you already have the internet up and running on your Amiga via the ethernet card), and you mean filesharing with your pc, then you should google for Amiga Samba.