Hi, 

> I read bsd.faq.3 for build my own kernel but my machine
> at /sys directory is emtry, never mind I get kernel \
> configuration from ftp.netbsd.org This file is INSTADP
> and I put kernel config(INSTADP) to /sys/i386/conf

On my system it's

NetBSD% pwd
/sys/arch/amiga/conf

Thus it should be 

/sys/arch/i386/conf

for you. Note that the configuration file is NOT all you need.
I am sure that there is a tar file on ftp.netbsd.org that 
will include all the stuff you need to recompile a kernel.
Reread the installation documention carefully. It should
say, which file you'll need to do that.

  Guenther