To start the server as a daemon, you should create a script something like this one, perhaps calling it startsmb.

#!/bin/sh
/usr/local/samba/sbin/smbd -D 
/usr/local/samba/sbin/winbindd -B
/usr/local/samba/sbin/nmbd -D 

Make it executable with chmod +x startsmb .

You can then run startsmb by hand or execute it from /etc/rc.local.

To kill it, send a kill signal to the processes nmbd and smbd.