Use your mouse or your touchscreen to move around the gallery. You can click on the symbol of the camera on the left bottom corner for an easy predetermined tour. If you want to stop or check any painting on the tour, click again on the camera and it will stop right where you are.
If you'd like to know more about a painting, click on the painting itself. The camera will take you right in front of it and on the right bottom corner of the window a button labeled "INFO" will show up.
And when you are ready to leave, you can exit by clicking on "EXIT".