how do i turn on my devices

Hello ciaran300,

It sonds like you are trying to enable Find my iPhone at www.icloud.com on one of your devices. In order to enable Find my iPhone you need to do so on the device itself. This article will help you do that:

iCloud: Set up Find My iPhone

http://support.apple.com/kb/ph2697

Set up an iOS device

1. On your device’s Home screen, tap Settings, then tap iCloud.If you’re asked to sign in, enter your Apple ID or, if you don’t have one, tap Get a Free Apple ID, then follow the instructions.
2. If Find My iPhone (or Find My iPad or Find My iPod) is turned off, tap to turn it on.

   Tip: For added security, set up a passcode that needs to be entered before anyone can access the apps and information on your device (Settings > General > Passcode Lock or Passcode & Fingerprint).

If you are wanting to turn on the device itself from www.icloud.com, this is not a feature of Find my iPhone. At www.icloud.com you can only put the device into Lost Mode, Play a sound on it, or Erase the phone.

Thank you for using Apple Support Communities.

All the best,

Sterling