Go to https://www.soldat.pl/en/ to download the game.

Extract, install, and start the game
Click on OK to select the default profile
Go to the "Player" tab at the top and change your player name and customise appearance
Go to the "Join Game" tab.  Request servers, scroll and look for "V4C".  Click on it and enter "nerds" in the password box at the top, and hit "Join Game"

Pick a team, choose a primary and secondary weapon.

Q to switch between primary and secondary
R to throw grenade
W to jump
X to prone
TAB enables and disables the weapon select menu while waiting for respawn