When you first log into your student email account, you may be brought directly into you inbox.
If so, locate and left-click on My account (this will be displayed by your name) in the top-right hand of the browser.
In the My account drop-down menu, click on "My account".
Locate and click the "Install Office" button, you will be asked to run or save the file.
From here, follow the prompts by clicking "Yes" to start the installation, and waiting while it downloads.
You will then be able to access it from your Start button under "All Programs" or if you are using Apple from "Finder", then "Applications".