of course it is a PG ka Dewana on having 500 post most easily accessible achievement. also PG post do not count in Chit chat section and intro so try to contribute in other sections too. its your Activity percentage as well how much you post on daily basis. its a gaming and hardware forum, contribute in both of them. you will have good experience while staying in PG community.
While other achievements needs time. just don't both with having no achievemen right now, keeep on contributing in forums and gradually you will understand rules about posting and achievement real soon. just give time.