basically there are two ways of solving it. The first is the explode the data into chunks and then converting them.

secondy, in my opinion the better and easier way:
use the function date("prefered format",mktime(...))
first arguments is you format that you like.
the secend argument created an unix-timestamp (look at http://de2.php.net/manual/en/function.mktime.php). it allows you to generate any date and time you like.