Please help, I have problems with Windows8.1 too

I just bought Arduino Starter Kit last week.I have installed Arduino and the Driver correctly(I can use Arduino and find the driver of Arduino Uno in the windows device manager).And there is nothing wrong with Java.I got my board(Arduino Uno) connected to the computer,the LEDs seems OK(Green one turned on and yellow one kept flashing,is that OK?).But the Arduino Serial port menu still greyed out(I restarted over and over again),and I couldn't find any new serial ports in the device manager.But I did found an Unknown USB device(I'm sure that's my Arduino Uno) when I was using virtual box.Can anyone help me with it please??

Hello!
Could you send a picture of the following?:
The board
The IDE (Arduino Program)
Then we could help you further.

Kind regards,
-Goldfile