Hey, i was setting up Parse push notification service in my RoR app, wanted to know, how do i create channel, to which user subscribe? and do i have to do client installations for android & iOS, how do i send to both kind of users?
Thanks in advance :)

For more on client side implementation, you can checkout article - http://www.androidhive.info... from my friend.
Otherwise official docs (https://www.parse.com/docs/) should help you.