I agree with mike. Sound like you installed the clutch release mechanism wrongly, so the throwout bearing is pressing against the spring by default. Try releasing the rod that goes through the lever arm that disengages the clutch. Releasing the rod should allow the push out bearing to move back off the spring and will put the pressure back on your clutch assembly. After you remove it, see if the clutch is engaged by default if not then I am afraid the clutch itself is installed wrongly.