Go to https://www.office.com
Click Sign In link (upper right)
firstname.lastname@example.org example: (email@example.com)
current password (that you use when logging into your school computers in the morning).
Office365 should now open. You can a list of recent documents. To view all of your cloud-based documents, click the MORE IN ONEDRIVE or GO TO ONEDRIVE links.
You can open any Office document and work on it via the web/Office365 environment.