The Galaxy Map can be found on the top level of the Normandy. To direct the ship to visit a new location, approach the holographic galaxy and press [ E ].
The Galaxy Map has four levels of detail. When opened, you will see the entire Milky Way, with various colonized clusters highlighted. From here you can zoom in through levels of detail by using the mouse to move the red "crosshairs" over a destination and clicking the [ Left Mouse Button ]. The levels of detail are:
>Planet / Ship
To zoom out, click the [ Right Mouse Button ].
At the Planet / Ship level, you will see an image of the location on the left, and a text description on the right. If there is something of interest in the area, an action button appears at the bottom of the text description.
The [ Survey ] button indicates there are anomalies in the area than can be investigated using the Normandy's sensors. The [ Land ] button indicates you can explore the planetary surface. The [ Board ] button is similar, but used to indicate you can explore the interior of a space-borne object, such as a ship or station.
Some Star Systems include hidden objects. These can be found by looking for flashing points of light and hovering the crosshairs over them. When the crosshairs are over a hidden object, click the [ Left Mouse Button ] to "scan" and reveal the object. Hidden objects are frequently -- but not always -- in asteroid belts.