It is called "The Truth About the Titanic" and vintage copies are not too hard to find. Dover Press has reproduced it I think in its paperback collection of survivor's stories. Let me see if I can find the link. Mike Tenarro can also give you advice. http://www.titanicbooksite.com/
There's also quite a bit of discussion about Gracie's book on this board. See the folder: Gracie/Beesley. While a number of vintage copies of Gracie's book are readily available through the used/antiquarian books circuit, a good and cheap option is the Dover paperback Shelley mentioned above. The paperback includes the full text of the Gracie and Beesley books, the Titanic excerpt from Lightoller's book and Harold Bride's account too. The text of Gracie's book doesn't seem to be available online yet - or at least not through Project Gutenberg. Happy hunting.
Gracie's book has been published under a variety of different titles, Mario. The original title was "The Truth About Titanic", but it has been released as "Titanic", "Titanic: A Survivor's Story", and who knows what else.