Answer:
Salut meilleur ami,
viens à ma fête d'anniversaire ou je t'enfonce un bâton dans le cul. merci <3
Cordialement,
(votre nom)
you can copy and paste if that would be easier.
(i am fluent in french and so i think this might help,
i wrote "hi best friend,
come to my birthday party there will be fun games and i even got a multi-layered cake. thank you <3
regards.
(your name)