How do I put a plane on a cylinder?

I need a plane on outside of a cylinder and rotated 20 degrees.  Attached is screen shot.  I am trying to insert a reference plane, but when I use the angle option it wants me to select a plane and an edge.  I have no edge to select.  I have tried inserting a centerline for an edge, but when I go into the reference plane command the line is not there.  How do I do this?

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