I can't get the car into reverse

I put a new transmission and a stage 2 clutch brand new in the transmission the transmission had 36 thousand miles on it I drove it home and now I can't get the car into reverse, it's like stopping and act like there's something stopping it, eventually it will go in but takes force, also when car is in neutral and not stepping on the clutch there is a knocking nee coming from the transmission.

I step on the clutch nee goes away, now it's gotten worse first gear like you go to put it in and it goes in but putting it in first it like tries to kick it out back at you it doesn't sound like it's grinding it sounds like it metal clanking together but feels like it doesn't want to go into that gear but it will, other then that it goes through the gears good, I have put 500 miles on it now and I'm afraid to go anymore I feel like I'm damaging my transmission more and more everyday since it seems to be getting worse. Please help!