Round parts

I'm trying to do a circular piece and i'm really stuck.
 It's something similar to the microptic 50, on themiddleright at this adress: http://afoptical.com/cat_2_12.html

Now, I can't find any way to put the horizontal holes attheirright places.  The only way I could figure would be tohave areference plane from which I could set angles, but I couldn'tfindout how to do that.

So, how do I place objects at the angle I want on acircularpart?

Thanks

VincentSolidworksParts And Features