How can I use the Firmware which is posted here??

I'm from Germany so my English isn't very well, but I got some questions:

1. If I want to pick a application from a firm ware which I've downloaded from here what I have to do??

2. How I'm able to match a firmware with my mobile phone (K550i)??

3. Do I need any software??

Thanks and Greetings from Germany :D

First read this XS++ 3.1 Guide-Flashing, Customizing, Recovering - Top Sony Forums and connect phone with XS,after that post log from XS here without IMEI number and than will see