Not sure what you are after here but eithe way, yes it is possible anky by WIFI. Do you want to:

a) Use the internet on your pc by connecting to your phone which is online
b) Use the internet on your phone by connecting it to your PC which is online

Solution:
a) Install Nokia PC Suite as it includes a tool to connect to your phone and use its data connection as a modem (can be done over cable or bluetooth)
b) Turn on Internet Connection Sharing on the ethernet connection and go into the properties for the wireless. Click advanced and change it to Ad-Hoc networks only. Then go out of that and click add. Make up a name (SSID) and set your security (I left mine open to begin with to make sure it works). On the phone, manually create an access point and put in the SSID you chose and whatever security it needs.

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