Read it, date it, and sign it. Print your name, email address, your country and position ("Volunteer" is fine if you don't have a position).
Scan or take a photo of your signed document (be sure that it is clearly legible).
Save your file, and name it like this: CC-NAME-ConfAgree.pdf (For example: MX-Smith-ConfAgree.pdf) CC is your ISO country code (AU, MX, CA, etc.). NAME is your Last Name. You can find the ISO code list here: http://www.nationsonline.org/oneworld/country_code_list.htm