i am building a simple PM for my personal website where a user can join and send message to the registered users on my website,

i am stuck in grouping and selecting latest user (by latest msg time) in INBOX page

my table :

id   msg_from   msg_to  msg   date   in_del   out_del

i want to show latest user's id each in a group

here is my SQL query :

SELECT ttalk.id, ttalk.msg_from,  users.first_name, users.last_name
FROM ttalk
INNER JOIN users ON ttalk.msg_from = users.id 
WHERE ttalk.msg_to = '$_SESSION[user_id]' AND ttalk.in_del='0'
GROUP BY ttalk.msg_from DESC LIMIT 500

Thanks in advance :-)