Ardiuno Uno newbie can't upload blink

Using Arduino IDE 1.x
1

I got an Arduino board from ebay and downloaded Arduino 1.6.5 to my windows XP computer. No luck so far.
I think I have the wrong port, how do I tell?
Also should know that it's not a %100 genuine UNO. It says on it
M.J.
M.Jduino UNO R3

Here's the error message with the lengthy part cut out -

Arduino: 1.6.5 (Windows XP), Board: "Arduino/Genuino Uno"

Sketch uses 1,030 bytes (3%) of program storage space. Maximum is 32,256 bytes.

Global variables use 9 bytes (0%) of dynamic memory, leaving 2,039 bytes for local variables. Maximum is 2,048 bytes.

avrdude: ser_open(): can't open device "\.\COM3": Access is denied.

2

Look in device manager, you should see the port number.
You may also need to install a driver for the Uno.

3

Probably the board driver isn't installed. Open Device manager and you probably have a ! under ports (or unknown devices). That board of yours uses a CH340 chip (nothing wrong with that). Drivers can be found here.

4

Much thanks to all, especially for the link Septillion.
I was missing the driver, and after installing it it was no problem to tell which port to use.
Uploads sketches no problem now.