TheCleanser

Those are "rank images", which are images that correspond to your current post rank. While, every member has a rank, rank images are only available to Premier Members; although premier membership perks are extended to all members during BZPower's anniversary week. You should be able to purchase premier membership at the BZPower store linked to at the top of this page.

Thank you very much for the answer.

You're welcome, if you have any more questions about BZPower you can ask them in the BZP Q&A sub-forum. In said sub-forum, you can also find the Q&A Compendium a great source for all things BZPower.