Create this new action from Setup, by clicking. Populate the Target Object and Standard Label Type fields so they match the settings in (1) and (2).
Then add the new action to the Publisher Actions section on the opportunity page layout. From Setup, click.
In Salesforce1, the action is available from the action menu on opportunity records. In versions of the downloadable apps that don't have the new action bar, users access the action from the publisher. The action is also available in the full Salesforce site, from the publisher on opportunities.