You will really have to work hard and it may take years to get it good enough for publishing.
For instance; there is already a book fitting that discription called, "Anastasia's Album". You probably already have it if you are really interested in Anastasia. That book had (for the time it was published) new pictures, many that were hand-colored by Anastasia herself, new letters, objects belonging to the family, and information that children and even adults would find interesting. If you want your book to be published it has to have those kinds of things. You can't just use the old run of the mill photographs and letters and information and expect a publisher to be interested in it.
That said, you should plan a trip to GARF and read as many books as you can.