You can use hotkeys to perform the same actions: 1 - 37% zoom; 2 - 50% zoom; 3 - 75% zoom; 4 - 100% zoom. You can also use the arrow keys on your keyboard to move about the map.
Using the Overview Map
Click on the "Overview" button to bring up the overview map. The red shaded box indicates which area the main map is showing. Left click on the overview map to move the main map around quickly.
Pressing o will bring up the world map overview.
Using the Key
Click on the "Key" button or press k to bring up the key. There are three pages in the key, clicking on the "Prev page" or "Next page" buttons will allow you to scroll between them. Clicking on any item in the key will locate all icons on the map of that type (they will flash yellow briefly).
Finding a Location
You can now click on the 'Find' button in the top left of the map or press the f key on your keyboard. Typing in a place name and hitting enter will then scroll the map to the location you have requested.
If you only see a grey square
Go to the Extra Files section on the website for a downloadable version of the map.