The problem with this BAPI is, that it calls ta XK01, so it is only possible to create a vendor in dialog. that's why this BAPI is not usable for creating vendors from outside the system (e.g. with java, etc.)
A code example is very simple, just provide a number for the vendor. the next thing which will happen is the dialog coming up (ta XK01). There you need to populate the mandatory fields in dialog mode.
You may test this bapi via ta se37 then you'll see, what I mean.