On the bottom right of the Internet Explorer screen,

click the arrow next to the Change Zoom Level button.
You will then see the following options:
To go to a predefined zoom level, click the percentage of enlargement or reduction you want.
- or -
To specify a custom level, click Custom. In the Percentage zoom box, type a zoom value, and then click OK.
If you have a mouse with a wheel, hold down the CTRL key, and then scroll the wheel to zoom in or out.
If you click the Change Zoom Level button, it will cycle through 100%, 125%, and 150%, giving you a quick enlargement of the webpage.