replacing sites w/ Trijicon sight on .40 cal P99

I have a Walther P99 .40 serial # 408371 which is about 5 years old. Purchased a set of Wpo1y Tijicon sites and need some help with instruction on repalcing them. The front sight has a slot with a round hole (not allen) in the center. the rear is the stock 2dot with the windage scew.

looking for tips on replacing both sights

Any recommendations ?