While The Magician's Nephew is the sixth book published as part of the Narnia Chronicles by C. S. Lewis, it is actually the first in chronology for the series--a prequel, if you will, to The Lion, the Witch, and the Wardrobe. From your question, I can't tell whether you've already read the book or if you're looking for some things to look for as you read. I'll try not to give away too many of the plot elements in case you haven't read, but either way, this is a book full of interesting and symbolic issues to think about and study.
The Chronicles are all allegorical in nature, so the primary element to look for in this novel is the allegory--the characters and places which represent things greater than themselves. Consider the following:
- Aslan sings and creates a world--from nothing.
- Jadis, the ice queen, is an enemy to Aslan.
- Aslan and Jadis are locked in a battle between good and evil.
- Gardens and an apple and temptation are all part of this story.
One other important thing to examine in this novel, especially if you're reading the entire Chronicles, is all the "beginnings" in this novel which carry over into the rest of the series. And if you're looking for something more in-depth to study and/or research, perhaps you could examine why this novel is out of chronological order in the series.