Use setup_warside.exe to install the game launcher.
You can choose English language, but translation isn’t ready so game will be in Russian anyway.
Launch the game, it will automatically start to download resources (Start > All Programs > Warside > Warside launcher).
You can adjust basic settings in options tab.
After update is finished, launch game by pressing play.
On loading screen, you can see random gameplay hints and game lore.
Login into the game using your login and password from site.