There is also a plugin to post through to an existing account on a Status.Net service. You do not require this to communicate with Status.Net members from Friendica - only if you wish to post to an existing account.
All three of these plugins require an account on the target network. In addition you (or typically the server administrator) will need to obtain an API key to provide authenticated access to your Friendica server.
Each of the connectors also requires an "API key" from the service you wish to connect with. Some plugins allow you to enter this information in the site administration pages, while others may require you to edit your configuration file (.htconfig.php). The method for obtaining these keys varies greatly - but almost always requires an existing account on the target service. Once installed, these API keys can usually be shared by all site members.
This can be done from the account settings under "Settings -> Connections -> Register an OAuth client application -> Register a new application" on the StatusNet server.
* Application names must be unique on the StatusNet site, so we recommend a Name of 'friendica-nnnn', replace 'nnnn' with a random number or your website name.
After the required credentials for the application are stored in the configuration you have to actually connect your Friendica account with StatusNet. This is done from the Settings -> Connector Settings page. Follow the Sign in with StatusNet button, allow access and then copy the security code into the box provided. Friendica will then try to acquire the final OAuth credentials from the API.
If successful the addon settings will allow you to select to post your public messages to your StatusNet account (have a look behind the little lock symbol beneath the status "editor" on your Home or Network pages).
Facebook contacts will also not be able to view "private" photos, as they are not able to authenticate to your site to establish identity. We will address this in a future release.