In the book I Am Malala, what devices or techniques does Malala use in order to tell her message to her international audience? Also, in what ways did she connect herself to the audience?

The biggest technique I can think of that accomplishes both of these tasks is personal anecdote. Through personal anecdotes, Malala gives readers an intimate look into her life. This both expresses her message and emphasizes that she is just a "normal girl [or kid]" like her readers are or once were.
For example, Malala begins with a retelling of the day she was shot by the Taliban. Rather than describing the event in a lofty or conceptual way, she tells the story personally. Her telling emphasizes that she was just a normal schoolgirl. She writes about her friends, about riding to school, and about classwork. These universal experiences are likely shared by her readers, who can easily relate. Personal anecdotes like this also strengthen her appeal to readers about the importance of education for all women and girls.