Accessing your calendar using Outlook on the web is done through your web browser. You will need to log into the Office 365 portal and click on the Outlook block on the Office 365 Home or in the app launcher:
Once you get into Outlook on the web, you first land in your email. You can access your calendar by clicking on the calendar icon:
Let's look at the parts of this interface:
In the previous screenshot, you can see the events for the month of February.