You could go about this one of two ways. The first option would be to edit the constituent record and insert the organizations name into the first name field of the constituent record. The last name field could be cleared out and left blank or include inc, llc, co, corp etc. The second option would involve creating a new constituent record and providing the organizations name into the first name field of the constituent record. The last name field could be cleared out and left blank or include inc, llc, co, corp etc. The transaction could then be moved from the record that it currently exists on to the new record you have created for the organization. In order to move the transaction please refer to this document for steps on how this can be done.