xs++ is a program used to flash the firmware of your phone. Flashign your firmware gets rid of operator logos n stuff. that vodafone, o2, tmobile etc like to put on phones.
Unlocking is easy on w810 but harder on new phones you just need to figure out what firmware you have, generate an unlock patch and then patch your phone.
first thing you need to fond is a sony ericsson usb flash driver
(i havent got a link for this but it shouldnt be hard to find is a phones use the same driver, i think its called ggsemc.dll)
You need to download xs++ or setools(recommended)
xs++ -- http://www.se-nse.net/gbrooks3/XS++/download.php
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One you figure out what firmware version you have you need to download it from somewhere it will be named R.. someting. for example "R4DB005" Setools or xs will tell you your firmware version
i have a link here for "R4DB005" firmware only
Download
if you cant find a link for your firmware then reflash your phone with this firmware(find a tutorial) ITS EASY
then make a patch from it using the sim-unlock generator in the link i provided
Sounds harder than it is :)