Google+: How to submit posts

After completing the registration process you have to add people to your circles. This can be done via drag and drop:

This is straigth forward. But how to write postings and submit them?
Google calls this "stream". You have to go back to your home:

Now add some text on the dialog in the middle:

and configure the circles to which this posting should be submitted. The four icons on the left are for adding a photo, video, link or your location. It is really nice, that you can configure, which circles get the postings.