Saint Law wrote...
A buddy told me that you need to grind for upgrades for your tank or just buy them so... is it like that?
Pretty much, you get your tank as a stock, as in a pre-set loadout of equipment. You play matches, earn xp, and spend those to upgrade certain modules for the tank, such as your engine or tracks, which affects the performance of your tank, and guns tend to get better as you upgrade(in higher tiers, guns tend to even out in performance, so it turns into a preference). Each tank has a tree for the modules, so you can have the stock engine, and two other engines you have to unlock to get to the next tank. As such, you need to unlock these in order.
Before you start the game, I suggest watching some tips for the game on youtube, considering some of the mechanics are never explained int eh actual game.