Is it right sentence?

English is a very complex language and there are many ways in which to write this sentence.
One way to say it would be:
John and Suzan are here, at my birthday party.
Or more simply - John and Suzan are at my birthday party.

This would be appropriate if you were pointing to a picture of a past birthday, doing a bit of reminiscing.

Susan or Suzanne are more common ways of spelling that name in English-speaking countries.

But of course, anyone can choose their own spelling of their name. Some people like to be different, or distinctive. Personally, I don't care for names being mucked about with.