Choose Home tab→Reference group→More Planes→By 3 Points button.
Select a point to define the reference plane's origin.
Select a second point to define the positive x-axis of the reference plane. The distance between point one and point two determines the width of the reference plane.
Select a third point to define the positive y direction of the reference plane. The perpendicular distance between the x-axis and point three determines the height of the reference plane.
You can use QuickPick to locate points.
The Keypoints option on the command bar can help you select points for reference plane creation.