How to install a saddle on a seatpost with a top facing bolt
You use the front bolt to set the angle first, then torque the rear bolt. Sometimes a few times to get it right.
The front bolt is adjusted with the thumbdial or a lever put into one of the holes in the thumbdial (eg 2.5mm allen key) when the rear bolt is fully slack. Hopefully it won't have blue loctite on it but if it does, you should remove it and replace with grease.
The thumbdial is shown in the second photo, the black, splined part on the bolt.