After an object is selected you can orbit around with mouse or touch. Enable Orbit mode with the following toolbar button.
After enable orbit mode you can then right click and move your mouse to orbit the object. Single finger down touch also orbits around the object.
Clicking this toolbar button moves the spectator to the PlayerStart you have added to your level. To add a PlayerStart to your level select it from the Place Actors area on the left and drag it into the viewport to add it to your level.