The create origin tool allows you to create a custom 3D frames of the same name as the node's name. If you know the precise position of the frame enter it into given fields. The orientation of that frame will be inherited from the frame specified under theFrame field.
However, it can be difficult to provide a 3D position so to get these filled out automatically you can use the RViz broadcast position option. Do this by clicking the Get Point button.
Next, broadcast points from RViz by right clicking the PR2's head, selecting Take Snapshot, then right clicking on a point in the snapshot that you want to broadcast and select Broadcast Click Position (you might have to do this more than once). The Create Origin tool will now be filled with your point. If this node then executes it will create a frame located at the given position with the inherited orientation.
Usage for Behaviors that Manipulate
Another use for this tool is to provide frames at run time for a behavior allowing entire motions to be described relative to a Broadcast Click Position command. For example, you can create a door opening or drawer opening behavior by creating a frame placed at the door or drawer's handle then creating a motion described in this new frame with the Velocity Priority tool.
To do this, instead of clicking Get Point, check the Wait for Point box. The Time Out field now specifies how long this node should wait for a Broadcast Click Position event to occur.
TODO: write a full tutorial for this.