also notice the colorscheme=light  this is for light backgrounds, if you change that to colorscheme=dark it will be for a dark background.  Dont forget
to change MYDOMAINNAME to your domain name (assuming you have your domain name account set up on facebook already)

<iframe src="http://www.facebook.com/plugins/like.php?href=http%3A%2F%2Fwww.MYDOMAINNAME.com%2Findex.php&amp;layout=standard&amp;show_faces=false&amp;width=200&amp;action=like&amp;colorscheme=light&amp;height="50" scrolling="no" frameborder="0" style="border:none; overflow:hidden; width:200px; padding:5px,0px,5px,15px; height:50px; text-align:right" allowTransparency="true"></iframe>