LED’s in a car?

I've got a 1994 Chevrolet Lumina I'm wanting to put LED's in, just as lighting for under the dash, but I've come across a snag. I've got LED's that are just regular LED's, 3.3 volt, I've got resistors for 12v operation, but something has confused me. How am I supposed to hook up LED's with a positive and a negative, into a car that only has 1 power cord, coming straight from the battery? How do I get the LED to light up, wheres the negative? Do I run a negative line from the battery as well?  Let me know, and also, lmk where I run the resistor from, if I were to hook up 5 LED's off of one line, I'd want to take the wire(s) from the battery, split it 5 ways, and on the positive, hook it up there before it reaches the LED? 

Wire the Leds in parallel so you only require one resistor, then attach the negative wire to the body of the car. Or do it your way, a wire for each led than ground an the chassis.

Will it still power even though the negative is just gounding? I know that's what its for but I thought... Well I'll try it. Explain to me what you mean by wire them in parrallel?