In each level, there will be a kill count that you’ll have to fulfill, so that you win and move further up. Of course, you will be rewarded with money that you can later use to unlock new vehicles.
There’s a total of 6 of them available. During the game, try not to crash into barrels, since they can explode and destroy your vehicle. Try to play tactically at first and push your enemies into them.
If the game lags at first, you can use the settings to lower your quality.