how to modify serialport portname and baudrate manually in c#

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C#

Hai,
I am doing one project for serial port read and write. It works fine but now i want to modify my serialport name and baudrate from my windows form through combobox. User want to select the portname and baudrate from combobox at that time my seialport property have to change based on combobox value.
For example now my project read and write data with serialport portname COM3 and baudrate 9600 by setting the properties of serialport control in my form. Now i want to change the property through combobox by selecting portname as COM1 that serialportname want to change and read and write data simultaneously...
Please help...
thanks in advance....