To create this widget you need to select Custom widget (last widget in dropdown add widget menu)

Segment: Organic Traffic

Dimension : Month of the Year (for example)

Metric: goal Completions All

You can choose to track all goals completion. 

Or you can choose to track organic traffic for specific goals:

In step 2, you can edit widget title, widget description, and select data to hide. 

During the last step you can choose the format and size of your GA widget.

Did this answer your question?