Com 11 not specified

I have an arduino from RadioShack and I just downloaded the latest program from Arduino. This problem has been there many times but now I'm sick of it can anyone help me? Here is the error message:

Arduino: 1.6.7 (Windows 7), 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 "\.\COM11": The system cannot find the file specified.

Problem uploading to board. See for suggestions.

This report would have more information with "Show verbose output during compilation" enabled in File > Preferences.

I would apprciate any help that I could get.

See if this helps: 1. device manager 2. select ports 3. select port of arduino board examle : com1 ... com3 whatever it is 4. right click on com. 5. select properties 6. tab- port settings 7. click advanced 8. com port number- select new port number that is not in use. 9. confirm.. save and continue