I have been trying to create an alarm application for my watch for past few days. And unable to find any clue that how we can create a background service for android wear. Even I didn't find anything in the developer guide for android wear.
But, I just want to create this application only for android wear and don't want to synchronize data from my cell phone.
Android Wear is based on the same architecture as regular Android phones. So if you want to create a background service, you do it exactly the same as you would on a phone.
For example, here is a tutorial on creating a background service: http://developer.android.com/training/run-background-service/index.html
And a stackoverflow question about background services: Creating Background Service in Android
If you want an app to run on the wearable, you will still need to provide a minimal phone application to deliver it to phones via Google Play. More information about packaging is here: https://developer.android.com/training/wearables/apps/packaging.html