You can sign in to Office 365 on your computer by opening a web browser and going to

Use your child’s email address and password supplied

Next, choose the location and time zone that are correct for your location from the dropdown lists, and click next. This may not appear if you have logged in at school previously.

You will then be presented with your personal area, starting with your welcome page. 

From here you can go direct to any of the online Office 365 applications. 

The top bar contains links to your various facilities; 
Outlook (email), CalendarPeople Teams,  OneDrive (documents folder), OneNote etc.