There’s a few things you’ll need to get watchOS 2 installed.
First, you must have iOS 9 beta installed on your iPhone (this requires your UDID to be activated). Later you will also need the UDID of your Apple Watch to be added as well.
To make it easy just use our provisioning service to activate both your UDID and Apple Watch for the beta!
Download Xcode beta 7 for free here.
Make sure your iPhone is connected to your Mac via the lightning cable. Now go to the Window menu and select the Devices panel. Select your iPhone in the Devices section to the left and then you’ll see the Apple Watch under it. Click and select the Unique Device Identifier (UDID) for the Apple Watch and then copy that number with Command+C.