That's for members who joined before April 1st 2012
Go to that member's profile, click the "statistics" tab, click "find all messeges posted by *username*". Go back to a post made in April first and check the page you are in. Each page holds exactly 15 messeges. so now find all the messeges in that page that have been made since april 1st onwards, Multiply the page number you are in minus 1 by 15 and then add the number of messeges in the page you are in that were posted from April 1st (day achievements were posted). That is the number of your posts since April 1st and the number you should use for the P1 and P2 achievements.
For example, since (8-1)*15 = 105, a screenshot of you being in page 8 of your post list and having a messege posted at april 1st there (assuming the order is descending chronologically) is sufficient to prove you achieved P1. Or you could just link to the page that has your april 1st posts in.
Don't post here saying you don't get it if it's not important for you.
