To unlock your first weapon you must gain 1,000 global points on ranked servers. You will not gain any of the points you have earned in a server unless you play until the round is over (until the map changes or a team wins). When you have reached over 1,000 global points in your BFHQ window, quit the game and return for a special pop up window congratulating you on your new rank and a message stating that you can now unlock your first weapon. Be very cautious on which one you unlock, as you will not be able to change it afterwards. The next rank requires 10,000 global points.