Turn a photo into silhouette

[kitkatdubs]

Can anyone guide me on how to turn this photo into a silhouette? I basically just want to whole dress to be black. Don't like the polka dots showing. I use photoshop ...

 

[KmH]

Use the Quick Selection tool and the Refine Edge tool option.
Outline what you want to be a silhouette and refine the edge.
With the selection active open a Exposure Adjustment layer.
Reduce the exposure until you have the amount of darkness you want.

Adobe quick selection tool
Refine Edge tool option
Adjustment layers