Somethings up with my car?

I have an 04 mustang GT with a 5 speed manual transmission and for some reason it's not grabbing the gear or something? It has a new clutch but everytime I let off it to engage a gear the RPMs go up but the car dosent go anywhere? The rpms will be at 3,000 in first gear and the car won't do more than 10 mph. Also everytime I push the clutch in I hear like a clanging sound? So if anybody could help me that would be great thank you