Important things to note when <em>writing</em> an informal letter.
Structure your <em>informal letter</em> like this:
Writer's address (also add the receiver's address if he is out of the country)
The Salutation. ( Dear Friend, etc)
Body of the letter: Here, you write the major reason why you are writing the letter. In this case, you are writing to him/her about the book which you like the most. With this in mind, you'll have to tell them why you like the book, why oyu would recommend it, what you have learnt from it, and many more.
The Conclusion: Here, you conclude your letter by asking some questions about how he or she is doing and ask him or her to write you back.
