It sounds like your clutch is not fully disengaging and the sounds you hear in the rear are gears dragging when you try to shift.
Your system probably still has air in it. Check pedal free travel, should be about 1/8 to 1/4 inch. Then try bleeding the system the old fashioned way with a helper inside the car to push the clutch pedal, while you open and close the bleeder valve. You need to do this several times to remove all the air.
