You can add the holidays here.
How to add Holidays.
Step 1: Go to “Setup”.
Step 2: Click “Add Holidays”.
Step 3 : Then click the option “Add new line” and enter the holiday occasion there.
Step 4: Select the “Date & Day”.
Step 5 : Click “Save” to add the holiday.
Holiday added successfully. The added holiday will be displayed in Holiday Calendar.