How to post as Character?

I noticed some people are able to post in a forum game as their *character* rather than their overall GP profile.

How do I do this?

The character needs to be submitted and approved in that forum/game. Once that process is complete, you will see a "Post as" drop-down menu where you can select either yourself or your character.

Also, the avatar must be uploaded to the character sheet (see top right of char sheet).