Stardates Explained - 19990811.1011

You don't understand the startdates?

Take, for example, 19990811.1011

Let me stick some spaces in some helpful places:

1999 08 11 . 10 11

That better?

19990811 means 11th August 1999, and 1011 is in 24-hour clock format, IE 10:11AM

Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.