If you are retrieving it from the database as a string (i.e. it is stored as a string rather than a DateTime field) then you have no choice but to break it into it's constituent parts sith Substring and reassemble it with the spaces where you want. But it would be a lot better to store it in a DateTime field instead as these are a lot more flexible.
If you store it as a DateTime, then all you need to do is specify the exact format you want when you convert it to a string for display:
Formatting a DateTime for display - format string description[
^] will help.