This is because Android Wear smartwatches don’t include on-screen keyboards, because it’s easier to enter text using voice recognition than it is to type on a device with a 1.6 inch screen.
Called the Analog Keyboard for Android Wear, it’s available for download from Microsoft Research.
It should be noted that the initial version of the app only supports smartwatches with 320 x 320 pixel square displays and the Motorola Moto 360. The installation process is also a little complicated and requires the Android SDK and a USB or Bluetooth connection between your PC and watch.
Microsoft is referring to the Analog Keyboard as a prototype… and for good reason. For instance, it currently only supports lower-case characters, not upper-case letters and doesn’t run on watches with 280 x 280 pixel screens. Microsoft says the keyboard can also be a battery hog, since all processing is done on your watch, not on your phone or in the cloud.