I really don't know what's happening when I hit the reverse it makes a.clicking sound does any one know what it might be
Probably your front ring and pinion gears.
Could be the rear ring and pinion gears.
Maybe something in the transmission, but I doubt it.
Check this out:
Setting up your bulkhead
Be sure to tear it down and inspect before you order parts, but usually just a ring and pinion will fix this issue... along with some shims to prevent it from happening again.
Whatever it is I just typed... could be wrong.