Letter to friend meeting after long time?

Just be simply and happy for having the opportunity to write to him/her. He/she is friend so not formal.
Here is simply format

                                                                                                  Matryin Benoit,
                                                                                                  New Yoke city
                                                                                                  house No-----
                                                                                                  10th November,2010
Dear Stephen,
                      how long it's been since we last wrote or even saw each other....
I really miss your company.....
Best wishes
MB

see it's easy.Try it