You can't post on our forums if you're on a Starter Edition account (except for Customer Support forums) or your Parental Controls settings block posting.
"Your account is inactive"
This message means your recurring payment is still pending, and posting privileges are restricted. This usually lasts for 24-48 hours.
Try clearing your internet browsers's cache, cookies, and browsing history to solve this issue. If that doesn't work, update your browser or try a different one.