xv commands

[Coran Fisher aka The Doctor]

Hi there I have a silly question about xv, I use xv to set my backgrounds
and there's just one thing I'd like to do that I don't quite understand.  I
use commands like xv -root picname.jpg  to make the picture my background
but if I do that it tiles the picture I'd like the command line similar to
the pull down menu root and centered I have unsuccesfully been trying
various commands I got from xv --help.  

Thanks!
Coran