My dear Name,
Today is your thirteenth birthday. Please accept my heartiest congratulations. A few months hence you will be a student of the ninth class and choose your subjects according to your plan and taste. I am confident that you will come up to the expectations of everyone in the house.
I wish I were with you on his happy occasion but I am far away. I am, therefore, sending you along with this a little parcel as a birthday gift. I am sure you will keep it as a token of love from your loving brother.
With many a happy return of the day for you.