For an email, there should be an email address which belongs to the person whom you're sending the mail to, then you need to put subject which is A title about why you're sending email to your friend.

After this you can start to write your email just as an simple essay.
You can add points such as:
#School sports day
#Teacher's Day Celebration
#Independence Day Celebration
#Reading Day
#School level competitions
#Award Giving Day

>I have attached a pic for an example...Hopefully it helps you...
Good Luck for your essay :-)