The correct answer to this open question is the following.
Invitation.
Dear friends,
I have wonderful news. I have been accepted to the Shivaji Medical College Nagpur.
It is a time for celebration for me and my family.
That is why I would like to invite you to my party on January 15, 16:00, at the community center ballroom, located next to the main square, downtown.
See you there,
Anita
This would be the basic idea for an informal invitation to Anitas' party. It is not a formal event, so that is why is written in simple, amicable terms. If the invitation was to teachers and administrative members of the school, the invitation should have been written in a more formal language.