Refreshtokens. Access token is short-lived and can be generated by using a refresh token. The detailed description how to obtain a new token you can find in this document.
Communityheader. Authorization header with access token must look like:
Authorization: Bearer eyJhbGciOiJIUzUxMiIsInR5cCI6IkpXVCJ9.eyJjaWQiOi...
Community- they short name of your Socialboards account. You define the short name in the 1st step in the Socialboards account creation process. You can also find it while browsing your Inbox in your browser, in this part of the URL: