Working this out myself. Here is what I have learned. Let me know how well it works.
You need wifi direct ON, and connect the phones (invite /accept etc) through SETTINGS/WIFI then bottom right three dots (like : but 3 dots), click Wi-Fi Direct. Searching begins, when the phone is found then connect.
Some apps just need NFC touch to do all this. Easier. Like WIFI SHOOT (I think it is in the video below).
For an Xperia to send and recieve files on WiFi Direct you need to have the same program (like Office Suite) open on both phones. Samsung has some built in functionality, HTC and Xperia need third party programs. Luckily Office Suite is built in to Xperia Z1.
Open the Wifi Direct app on both phones. If you are using Xperias, then:
1) open OFFICE SUITE on the RECEIVER PHONE
2) on SENDER PHONE open FILE COMMANDER
3) select the file, select SEND FILE, then select OfficeSuite Wi-Fi Direct.
http://www.youtube.com/watch?v=XT-0oUtVOpg
