Answer:
Hello, (insert name here)
The 15 of October is my birthday (or put whatever date it is in). I'm organizing a party for all my friends to celebrate that day.
The place we celebrate is at... (fill in the blank, and at this time. We'll have cake, games, dance dinner, and more! I'm looking forward to having your company. Your company will make my day even more cherished for me.
Your friend,
(Fill in the blank)
You are invited