Hello, I'm using "Menschen - Deutsch als Fremdsprache" this book have different levels, so you can choose one for your best! 

thank u so much to all answers

And if it is your first foreign language you can start reading from 3-4th month of learning and start from a very easy texts.  If it is your 2-3-4th foreign language you can start reading from the 3-4th week already   

To Kimtaro - Correct! Right you are ! Depends on the level .. I just do not know good easy German original books ( however there should be many of them// I remember Children Books sections in Berlin and Munchen- were very nice!  Really think for the Starter(Level  A1-B1)  it does not really matter what the origin of his book is.. Just should be simple - you should understand about 60-70% 

@John: It depends on his language level. Some children books are even hard to read. He is learning german. Its better if he reads a book from a german author whose the original language is german.