A TIME data type is stored as a signed integer number of milliseconds in 2's complement format. This is not S5Time format as some of the other comments have suggested.
Using VB is quite simple and you could get some examples from the siemens A&D website. You will however need some OPC complient software Simatic net industrial ethernet, so that your PLC can communicate with your VB application. If you already have a winCC application you may already have this...