•
Switch into Sweep Surface Creation mode by
pressing the Sweep Mode Tool 
or by selecting "Sweep Mode" from the
Surfaces sub-menu (ribbon toolbar’s Create Tab).
The cursor will change to the sweep surface cursor.
• Select the object to be 'swept' (sometimes called the section or cross-section curve) from a photo, 3D view or table. Object types that can be used in a sweep are curves, lines and edges.
The selected object will highlight The closest end point of this object will be moved to the start of the next object selected and 'dragged' or 'swept' along it to define a surface. Note: if you do not want to use the closest end point as the connecting end of the two objects you can use the "Reverse Last Object" command, from the Surface sub-men, and the opposite end will be used.
• Select the object to sweep along (sometimes called the rail or trajectory curve) from a photo, 3D view or table.
The second object will highlight and the surface will be created. Note: the direction a sweep faces is determined by the direction of the objects being swept along. If the surface you create does not face the direction you would like you can use the "Flip Surface(s)" command, located on the surface sub-menu. This command will flip the currently selected or, if no surfaces are selected, the last created Surface. Surfaces also have a "double sided" property that will mean a surface 'faces' in both directions. See Surface Properties.