Noticed you are speechless today....me too
I can't send any messages at the moment, so i have to post a comment, but at the top of the profile page of the person you are sending the private message to, right under their picture you just click on SEND PRIVATE MESSAGE. The same screen will show up as if you were just to reply to a message that they already sent you. Hope that answered your question and i hope to hear from you soon!
Love you,
nistelahya