Netis 11n isn't actually a device, but a common driver for Netis products. You will have to manually visit the page below. Choose your device by using the available drop down menus. You need to locate the product model of your Netis device and then download the necessary driver.
Support page: http://www.netis-systems.com/en/Downloads/
Once the driver is found, save it to your PC and launch its installation. Follow the instructions on screen and everything should be OK.