To install simply navigate to your game directory for steam users its, program files/steam/steamapps/common/mountandbladewarband/modules. Once in modules pick the module you want the new crosshair on. Once you have picked your module in this case NW simply go to the texture folder and drop the file in. Make sure to create a backup of your old crosshair before overwriting.
If you'd like your own colored crosshair feel free to send me a message.
If you'd like your own colored crosshair feel free to send me a message.