Expanding your date range (to show all task in a specific date range) can be done in two ways.
1) Using the Date Picker
Click on Expanded View to see All 5 Calendars (on Regular View you only see 3)
Click on the Date Picker below the Calendars
This will give you the option of selecting the start date and end date of your "Date Range"
Select the First Date then use the < and > arrows to either move back or forward to select your second date. Typically you pick the earliest date first
Now, pick your second date, once you've selected that date the calendar will release and your Date Range has been chosen!