Q: how can i get messages to show both on ipad and iphone6

Have you linked your iPhone number to Messages on the iPad so that you can use it as your contact number on the iPad as well as the phone? On your iPad go to Settings>Messages>Send & Receive at>You can be reached by iMessages at>Select your iPhone number. If the phone number doesn't appear in the settings, take a look at this.

iOS and OS X: Link your phone number and Apple ID for use with FaceTime and iMessage - Apple Support