The below information (in black) is from the OWL Purdue MLA Formatting and Style Guide.
Note: If the website begins with https://, that portion of the url can be omitted and the url can begin with www.
Information needed for your citation:
Provide the artist's name, the work of art italicized, the date of creation, the institution and city where the work is housed. Follow this initial entry with the name of the Website in italics, and the date of access.
Goya, Francisco. The Family of Charles IV. 1800. Museo Nacional del Prado, Madrid. Museo Nacional del Prado, www.museodelprado.es/en/the-collection/art-work/the-family-of-carlos-iv/f47898fc-aa1c-48f6-a779-71759e417e74. Accessed 22 May 2006.
Klee, Paul. Twittering Machine. 1922. Museum of Modern Art, New York. The Artchive, www.artchive.com/artchive/K/klee/twittering_machine.jpg.html. Accessed May 2006.
If the work/image cited is available on the web only, then provide the name of the artist, the title of the work, and then follow the citation format for a website. If the work is posted via a username, use that username for the author.
Adams, Clifton R. “People Relax Beside a Swimming Pool at a Country Estate Near Phoenix, Arizona, 1928.” Found, National Geographic Creative, 2 June 2016, natgeofound.tumblr.com/.