Hi,
If you wish to transfer files, I suggest that you go to settings > Xperia connectivity > USB connectivity > Wireless media transfer - pair to PC.
If you wish to share your media files over DLNA you can setup your phone as a media server under settings > Xperia connectivity > media server settings. You will also need to have a program on your PC that support this. See more information on the following link:
http://talk.sonymobile.com/t5/FAQ/DLNA/m-p/351822#U351822
