...
Create New Sketch in the XY Plane
In this step we will create a new sketch on the XY Plane. This step is required for the boolean operation that we will carry out later in the geometry process.
Click on XYPlane in the Tree Outline and it should highlight blue. Then click on the New Sketch, .
...
Outer Circle Surface Body Creation
In this step the Surface Body will be created as a frozen, such that it does not merge with the inner circle surface body.
Concept > Surfaces From Sketches.
Set the Base Object to Sketch 2 (located underneath XYPlane in the Tree). Then set Operation to Add Frozen as shown in the image below.
\
Then, click Generate
...