There are several ways to zoom in and out of the map. Lets go through each of them.
Zoom bar
In the bottom right corner of the Navigator window the current scale is shown, with the zoom bar next to it.
Moving the slider changes the magnification of the map. Move the slider to the left to zoom in on the map and to the right to zoom out. The scale bar will automatically adjust to give a correct reading. This method zooms in/out of the centre point of the map view.
Toolbar zoom buttons
Clicking the first two of the above buttons in the toolbar will zoom out (increasing area shown on the map by one third) or zoom in (decreasing the area shown by one third). Click the third button to zoom to maximum detail the last button to display the whole map.
Click and drag
First you must change the cursor mode to Zoom in/out. Now you can 'click and drag' anywhere on the map. As you drag across the map you will see that a rectangular region is shown on the map and that the cursor has changed.
This signifies the zoom area. Once you have released the mouse button you have two options. Click inside this rectangle to zoom in to it, or click outside it to zoom out. The smaller the region the larger the factor of zoom will be.
Key shortcuts
The F5 and F6 keys can be used to zoom in and out of the map quickly. Press F5 to zoom in and F6 to zoom out.