Tyicel

Whenever I try to join a server for the DayZ mod they all say that they require a version of the Arma2 (either 1.61.94876 or 1.62.95168), but it says i either have verison 1.61 or 1.62. Apparently my version is constantly changing. When i went to the website to get the latest version of the beta it asked for a username and password to access the files, I am running Arma2 on Steam. Please help