when i start my car and let out the clutch i get this loud clicking noise but when i push the clutch back in it stops. also it pops out of second and fourth gear. Any ideas?

Start with checkign your shifter cables under the hood. Since the two symtoms can be directly related, if the cable has come loose it may not be getting the shift level into gear all the way and you might be hearing the shift lever slapping around.

Otherwise i would say it could be the thorwout bearing making noise or something loose in the trans.