Yes that's right, from the time you create your you only have 14 activity to be done, even you have made 20 posts, your activity remains in 14, wait for the updates(every 2 week) to be added your account of 14 activity again. So every updates your activity are increase or to be added a 14 activity. So to be rank up , newbie - Jr. Member you need to have at least 30 activity to rank up and become Jr. Member.

Jr. Member = 30 activity
Member =  60 activity
Full member = 120 activity
Sr. Member = 240 activity
Hero member = 480 activity
Legendary = 860 activity