The Calendar tool links to all other tools in D2L which have start, end or due date options. This means that once set, these dates will appear automatically in the Calendar. You can also add your own calendar entries to remind students of other due dates, etc. that might not be tied to a tool in D2L. Below are tutorials on how to use the Calendar tool.
Tutorials for students related to the Calendar tool specifically are at the bottom of this page (and also on the D2L for Students page).