The check-in happens through a Google form. The monthly check-in post and the newsletter have a link to the form where you will be asked to supply your username, your pledge level, and your current pledge total for the year. After you submit your information, the moderators record your numbers in the Pledge Progress spreadsheet. We use this data to spot trends in the group and we keep a record of how many millions of words and thousands of days GYWO writers have written over the years.
We strongly recommend you track the !monthly check-in tag on Dreamwidth, follow the Check-In Calendar, whitelist our newsletter, or make note on your personal calendar that check-ins are always open during the first five days of every month.