Entering my own tracking ID

[coolshots]

Ok here we go,
I need to enter my own tracking ID, the tracking ID i have will allways be different. So what i need is a new box on the new ticket screen which has ticket ID = "123123dasda234234"

Now then if i enter one that is all ready there i need it to tell me that that record has allready been posted.

Im hoping someone could help.

I do have slight knowledge of php.

Thanks

Sion