Help - Dynamic Map Zoom
To zoom in and out of map, left click the mouse button over the map slider on the left side of the map and move mouse up to zoom in or move down to zoom out. Likewise, select the plus sign at the top of the slide bar to zoom in or click on the minus sign at the bottom to zoom out.
If you are using a mouse with a wheel scroll button, you may use it to zoom in and out. Simply position the mouse over the portion of the map you would like zoomed, and then scroll the button up to zoom in, and down to zoom out.