how do I insert after a query???

I want to make a query weather a customer exists(by name with user input entry) and if not...want to
create a new customer which will prompt for the name and any other details that are available.
Can someone please put me on the right track. My customer table is like this:

Name                            Null?    Type
------------------------------- -------- ----
CUSTID                                   NUMBER(4)
PHONE                                    NUMBER(7)
NAME                                     VARCHAR2(15)
ADDRESS                                  VARCHAR2(15)
BILLING_TYPE                             VARCHAR2(3)
BANKAC                                   VARCHAR2(10)
CONNECTION_DATE                          DATE
DECODERID                                NUMBER(4)
DISCON                                   DATE

Katt Received on Tue Apr 28 1998 - 19:56:34 CDT