Unable to create surface with bsurface addon I'm using bsurface addon.

With the curve circle I have made some shape.
And add a  normal plane 

I click on the curve and then shift selected the plane and press tab to go in edit mode
Then I click on add surface and I'm getting this error

All splines must be bezier

Im unable to create the surface.Any solution
Set Bezier spline type for your curves.

As the warning is saying, you need to work with "bezier" spline type. They are currently "poly" type (probably because you created the curves from mesh conversion, and by default poly is the choosen type).

Select all the curves and click the button you can find in the tool shelf under the Curve Tools section. A menu will pop up letting you choose the spline type for the selected curves.