With a guide, you take a train to Tsarskoye Selo — the town where Catherine Palace is located. Alternatively, you can travel by metro and bus. From the station to the palace you can take a bus or walk (it's about 15 minutes).
After arriving at the complex, together with the guide you will go through the park area and then into the palace itself. The tour includes the famous Amber Room. Your will have a chance to enjoy the interiors and decorations of imperial Russia at its fullest.
When the Catherine Palace tour ends you can take a walk in the parks (if the weather conditions are appropriate) or go back to the city by bus or train. The guide will accompany you to the metro station and makes sure you get back to the hotel or any other end point you prefer.