Convert free form surface into plane

Hi there,
I want to make a rectangle in the curve (along with the curve). And the rectangle component needs a plane which is my free form curve drown in Grasshopper. But I can’t convert my surface into the plane for drawing rectangle. Any idea how can I fix it?
Thanks in advance.

You understand what a plane is?

Thanks for your reply.
I think the plane is the base of the rectangle. Isn’t it?
Actually, I want to create some overlapping planks through that curve like this picture. But I don’t know how is it possible?
Name ID Description Type
Surface S Base surface Surface
Point uv {uv} coordinate to evaluate Point

Name ID Description Type
Point P Point at {uv} Point
Normal N Normal at {uv} Vector
U direction U U direction at {uv} Vector
V direction V V direction at {uv} Vector
Frame F Frame at {uv} Plane

The "Frame"s are tangent planes at the points on the surface .
You will have to manpiulate them probably to get them perpendicular then .
Then , use those for your base planes for the Rectangle component .

Finally , Sweep & Cap to get closed BREPs .