Sketch Plane
Select a sketch tool, then select a sketch plane to begin sketching.
A sketch plane can be a global plane, a user-created reference plane, or a planar face of an existing part.
 Figure 1. Global Planes
        Figure 1. Global Planes Figure 2. User-Defined Reference Plane
        Figure 2. User-Defined Reference Plane Figure 3. Planar Face on an Existing Part
        Figure 3. Planar Face on an Existing Part