We are looking forward to Celebrate the Diwali with you and I Hope You will Come and Join Us
How do I write an invite for a friend for deepavali festival?
Depends how you are sending the Deepavali festival invitations out.
If it's a close friend, then an informal message or an instant message should be fine. Just say I want to celebrate with you, here's the plan....
If it's someone you are not close friends with, you may want to send a more formal letter or something that is official like a flyer with details of the Deepavali festivities.