When constructing perpendicular lines with a compass and straightedge, how should you start the construction?

1.) Draw a line segment somewhere on the paper and label it line m.
2.) Mark a point somewhere on the paper but not on the line, label this point r.
3.) Fold the paper on point r. Make sure the line is folded in top of itself
4.)Trace the fold with your pencil/pen
5.) label the intersection point P