Ah, help is the forum for this. But seeing as i'm nice i'll tell you.
¤ Open a server (This must be your server to do this)
¤ When spawned (Being spawned is very important) press F11
¤ When the world editor is open (Aka the F11 menu) press F4
¤ Nearish to the bottom right there should be four categories, what you want is Shapes
¤ Now Shapes has been split, you want Vehicles
¤ Then there should be a list of vehicles for you to use.
IMPORTANT NOTE: The skivehicle and deathvehicle are not useable vehicles. You will find out about them later on if you decide to take up coding.