For more, see Zoom Tools
To activate: Toolbar, or View menu / Zoom
Define a rectangular area in the map view to be viewed more closely.
Activate Zoom Window tool. The pointer becomes a magnifying glass with a plus sign.
Move the pointer to one corner of the area that you wish to view more closely.
Click and Hold and then drag the pointer across the map view to the other side of the area to be viewed and then release.
The map view will change to show the area defined by the zoom window at greater magnification.