@sillylilli05 Hey! So, you have an Inbox (which were all your pm are), to get there, on the top right corner it has your profile picture, click on it, and you'll see
Profile
-----------
Inbox
Notifications
Newsfeed
Works
Library
and other stuff
then you click Inbox and that's how you get there. but to pm someone you go to their profile and you'll see the following/unfollow box, the message box, and the mute/report box. You press the message box and type anything you want to say then press send. That's how you do it!