Online : Calendar
You can access the Microsoft 365 Portal by visiting https://login.microsoftonline.com and sign in with your account username and password.
On the left menu, click on All Apps then the Calendar app.
To quickly create a new event on your calendar, single click on a date, enter the details of the event then Save.
To create a new event in more detail, double click on a date, enter the details of the event then Save or if you add recipients to the meeting Send and this will send the meeting request to those invitees.
After creating your event you will see it listed on your selected date in your Calendar.
Tip: You can edit the event's at any time by single clicking on it to quick edit, or double click on it to edit in more detail.