i want to create a surface on that shape and i dont find how to do it ?
You could create curves-on-surface on that shape, and then use them to build a surface on it.
Welcome to Rhino.
You need to make a surface that is wider than the “cut” you want to remove.
(Think of surfaces as sheets of paper with four sides and then you can cut parts away)
So try to draw the full outer lines and then trim away a rectangle.
Once you have the four edges use sweep2 or surface from four edges.
In top view draw a rectangle and use Trim to cut the surface. (Make the rectangle larger than it needs to be to make sure you don’t have overlapping edges that might give you issues if they are not perfect. Remember Rhino has a tolerance of 0.001 mm or what ever unit and tolerance you use.
In the future supply a rhino file with the data needed to assist you.
Good luck!
In Rhino,
please go to help>learn rhino>tutorials and samples> level 1 and level 2 pdf
this is the manual. No one reads the manual, (but everyone should)
it’s the best /fastest way to get up to speed with Rhino.