A museum catalog is typically a book written in regards to a current exhibition. Yours should have an introduction to your exhibit and the big picture along with images of your exhibit pieces with text to contextualize the image within your big picture/theme.
Hundreds of digitized catalogs from special exhibitions that have taken place a The Met since the 1870s. This is a growing collection. Due to copyright restrictions the only catalogs digitized are those which The Met owns the copyright or which are in the public domain.
This guide from the Claremont College Libraries provides tools and tips for curating and exhibiting materials responsibly with tips on how to follow copyright, fair use, and licensing.