Activate this option by manually closing the cover or using a magnet on the iPad. The switch is in the upper right corner of iPad about 2 inches down. Once you activate it, then the option will be available in settings.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.