yes you should have both on, thick one first then thin one on top with the black side facing up.
for the non start problem, check your valve timing. the cam pullies have two holes in them for the keyway on the cams (roll pin) and they need to go on the cams the right way round, no disrespect but most people get it wrong.
Starting with the inlet cam, fit the sprocket with the "in" hole on the keyway and turn the sprocket till the "inlet" mark faces forwards (towards the front of the car)
For the exhaust cam and sprocket, fit the sprocket to the cam with the "ex" hole on the keyway then turn the sprocket till the "exhaust" mark faces the "inlet" mark of the inlet cam.
The crank is timed in the safe position, line the mark on the crank pulley straight up to the mark on the timing cover (12 o'clock)
If you have the cam sprockets mixed up and on the wrong way, no damage will result so dont worry about bending valves if it is wrong.