I am trying to get data from the serial port

I have built a simple serial program that opens the port and displays to a text box. It is working in that it opens and closes the port alright.

BUT the data some how needs to be converted. It is garbled the data is in 8bit bytes how do I get them to show in hexdecimal? This is what they should look like in hex values, 19 39 43 09 29 11 19 80 they represent the (hour, minutes,...