You need to have a Google account.
Step 1:
On your PC, login to your Google
Calendar, at "Other Calendar", select "Holidays in
Singapore"
Step 2:
On your phone, click on Samsung
"S Planner", tap on the menu button (bottom
left), click on
"Calendars", under your email, Tick "Holidays in
Singapore".
Step 3:
Switch on the phone's wifi/data
connection.
Sync with
your Google Calendar.
Go to Phone's settings -> General ->
Accounts -> Google -> your email -> Sync
Calendar
After successful sync, your
Samsung's calendar will show the holidays.