how do you turn on printer in iCloud

iCloud has nothing to do with printers.

You can print per the device you are using. If you are using a computer, you will need to set up your printer on the computer and print form iCloud.com or where ever you wish to print just like you would print anything else fomr your computer.

To print form your iOS device, you can use AirPrint. The printer has to be an AirPrint Printer and the iOS device and the printer have to be conencted to the same wifi to work.

Here's more info on Airprint and a list of all AirPrint Printers: http://support.apple.com/kb/ht4356