To use telemetrics, not that I knew how to use telemetric data for improvements, first I need to know how to create, download and check this data!
Can please anybody help me?!?!

Race on, Bemsofix

You can use the raf output in singleplayer replays. Just load a replay and take a look at the menu. Then, there are already some programs to analyze this output, like "analyze for speed".

[EDIT]
just for the case you wont find it:
http://www.liveforspeed.net/?page=analysers