Write the manuscript for your art book. Keep the text minimal. Start with an introduction that tells who you are, how long you've been doing art, what medium you prefer to work in, and a little about what readers can expect from the book in hand. Write a brief description of each piece of art that will be presented in the book. Be sure to mark where each photograph will go in the manuscript, but don't actually insert the images. This will be left to the publisher.
Take high-quality photographs of the art work you wish to include in your art book. You might even consider having prints made if the images don't photograph well. You can have prints of your art work made at a local print shop.
Consult a directory of publishers interested in publishing art books. Browse the directory and select a couple of publishers that appear to be suited for the type of art book you want to publish. Refer to the submission guidelines of each publisher when you submit your work. The guidelines will state how to submit your manuscript and images, how long it will take for a response, what the terms of payment for your work are, and where to send your manuscript for consideration.
Write a query letter to a publisher when there are no submission guidelines available. State in the letter who you are, briefly, any publishing credits you have, and describe the work you would like the publisher to consider. Address your query to the acquisitions department if you don't have an editor's name.
Consider using an online book design service to publish your art book on your own. Prepare your manuscript fully. Write the text and insert the images in the book as you want them to appear. The manuscript should be readied for publication and edited by you when you are publishing your book with a design service.
Choose the book design service you want to use. There are several such services available (see resources). Create an account and design your book using web-based tools that allow you to select cover and binding style, paper type, size, and layout.
Upload your completed art book manuscript, fill in an order form for the number of books you'd like to have made, and place your order. The book design company will print your manuscript as a professionally-bound art book ready for distribution.