One of the most important lessons a mechanic can learn is to quit while he's behind. Odds are that you're trying to fit a freewheel onto a freehub as noted by Anklework. In any case you shouldn't have removed the axle, and are very obviously in over your head.

Put the axle back on, and read a tutorial on "adjusting hub cones", to get back to where you started. Then (or maybe before) have someone look at the two parts and confirm your problem is that the cassette is a freewheel.