Choose Surfacing tab→Curves group→Contour Curve 
.
Select the surface on which you want to draw the curve and then click the Accept (checkmark) button on the command bar. You can use the Select option to draw the curve on a face or a face chain.
Click on the points you want to use to define the curve and then click the Accept (checkmark) button on the command bar.
Finish the feature.
Tip:
During the Draw Points step, you can use options on the command bar to construct either an open or closed curve.
You can use the Insert Point button on the command bar to insert additional points into the curve. To delete a point from the curve, hold the SHIFT button and click on the point or click the right mouse button on the point.
You can connect a keypoint and an existing keypoint. To connect the keypoints, click the right mouse button on the existing keypoint and follow the prompts.
You can delete the connect relationships on a keypoint so that you can drag the keypoint on a face. To delete the relationship, click the right mouse button on the relationship and follow the prompts.
You can drag an existing point to a new location on the face.
When drawing a curve across faces that are not tangent, you must place a point at the shared edge.