Simple! Just write a poem a day, every day, for the month of April. You can keep these poems to yourself, or post them online. If you want to be on the official NaPoWriMo participants' list, email your name and/or the name of the website where you'll be posting your poems to napowrimo2010 AT gmail DOT com. I'll link to your site on our main page, and you'll be able to follow along with other poets' trials and travails as they attempt to keep the ball rolling.
Want to organize your own local NaPoWriMo club or event? Go right ahead! There is no licensing, etc. NaPoWriMo wants to be be free!
Want to flaunt your NaPo-Prowess? The amazing poet Ivy Alvarez has created a bunch of buttons, in both national and international (IntPoWriMo) flavors. Grab one here or make your own. Let me know if you do, and I'll post a link. Need more information? Drop me a line at napowrimo2010 AT gmail DOT com.