BAPI......How to use custom and system defined Bapi's...

Hi All,

1. I have created a Bapi named 'zbapi_str'.

It appears in the Bapi interface (Tcode BAPI).

But , i cannnot find out . how to use this object.

2. There are system Defined Bapi's also. ..How to use them..

Plz give me some step wise details....

Regards.

Manoj