I don't think this is the only or even necessarily the best way to encapsulate a date, but it's really straightforward from what I see.
http://msdn.microsoft.com/en-US/library/by5d3kb1(v=VS.80).aspx[
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GetCurrentTime gets the current time. SetDateTime sets it. Operator +, -, +=, -=, means you can add them together. The Format method lets you build a formatted version for display.