Display day, hour, minute, second below per message

For specific characters of the forum which I am managing is to display clearly the time immediately after opening a new topic or replying to a topic.
Under each topic, or answers to a topic, "Yesterday at 2:39 PM", "12 minutes ago", and "A moment ago," always appear. I want time to be displayed as hour:minute:seconds day/month/year (Example: 23:49:50 16/02/2013) below the article. It is displayed immediately after a topic is shown or when there is a reply to a topic. Furthermore, I want to insert a line of time (hour:minute:seconds day/month/year) below each message.
I thought that Locale.php file (library/XenForo/Locale.php) may be edited but I do not know how to edit.
Please! help me.
I thank you very much.