Combo Box

[Guest_imported]

I try to create a combo box of my Database's key field. but How do I created it so that I can retrieve existing records and be able to add new record to my Database....some body suggest that I should create 2 combox: one with bound and in edit mode and another with unbound and in append mode and put one box on another...but I don't know how to do it..
any suggestion would be helpful...

thanks in advances,