how to translate

hi there! id like to translate some docs parts into russian but i got no idea how to get started translating ive read through some docs on translating out here but i still dont quite follow what exacly i need to begin translating the docs and where exacly may i find docs samples intended for translation? also there're some things which are of interest to me: how you guys control the translating process itself? that is: is there a guarantee that a file im going to translate is not already being translated by someone else ? ps/ it would be great if you provide guide to translating in greater detail ( for n00bs) cuz being one sucks thanks, regards