I'm not sure what your question is, are you just looking for the SQL statement?
SELECT * FROM pm1_users
INNER JOIN pm1_admin_Chat ON pm1_users.UserID = pm1_admin_Chat.UserID
INNER JOIN pm1_admin_Chat_history ON pm1_users.UserID = pm1_admin_Chat_history.UserID
see the following page for more details on join queries:
sql_join.asp