saddle position

[skinimini]

I just installed my new saddle, but can't figure out how to adjust the tilt. I think if I could tilt down just a bit, the position will be just about right. (see pictures below)

There are two circular knobs with grooves in which the saddle rests. I can slide the saddle front to rear, but attempts to tilt have not worked. Anyone know how to make these adjustments? Any comments in general about seat position?

Thanks for any help you can give.