How to count the number of messages per user in php

I have a table users with (id,name) and user_messages(m_id,user_id,msg_seen) and now i want to count the number of messages per user(like whatsapp)how to write a sql query for that? i have bulded it for a user who has looged in and now i want to show the number of messages per user?I mean i want to show me the amount of messagges which were send by other users