You can join the project here
If you like to take actively part in the organization and you can use some of your time on the project, there are many different administrative and promotional tasks in which you can help. Please write to firstname.lastname@example.org for more information.
If you have a website you can promote the event by linking it with a logo you can find in the download page.
If you are an art lover, you can plan something to do on the 20th of January that doesn't involve art, and take your artists friends or aficionados with you. For authentic art lovers an appropriated plan will be necessarily and sadly sort of boring and dull.
If art doesn't interest you, you neither interest us, so the organization of International Day without Art doesn't give a damn what you do or don't.
In any case do not forget that inactivity is in the essence of the project.