Information on how to contest a citation should be on the back of the citation or on the parking authority website.
Here is the text of the section:
811.570 Improperly positioning parallel parked vehicle; exception; affirmative defense; penalty. (1) A person commits the offense of improperly positioning a parallel parked vehicle if:
(a) The person stops or parks a vehicle on a highway where parallel parking is permitted and the vehicle is not parked in accordance with the following:
(A) Upon a two-way highway, the vehicle shall be positioned so that the right-hand wheels are parallel to and within 12 inches of the right curb or, if none, as close as possible to the right edge of the right shoulder.
(B) On a one-way highway where parallel parking is permitted on either side, a vehicle parked or stopped on the right side shall be positioned in accordance with the requirements of subparagraph (A) of this paragraph and a vehicle parked or stopped on the left side shall be positioned so that the left-hand wheels are parallel to and within 12 inches of the left curb or, if none, as close as possible to the left edge of the left shoulder.
(C) Where marked parking spaces are provided, a vehicle shall be positioned so that it faces in the direction in which vehicles in the adjacent lane of the roadway are required to travel and so that the wheels are within the parking space markings which are parallel to the curb or, if none, to the edge of the shoulder; or
(b) The person is the owner of an unattended vehicle parked on a highway in violation of paragraph (a) of this subsection.
(2) The provisions of this section do not apply to the driver of a vehicle that is disabled in such manner and to such extent that the driver cannot avoid stopping or temporarily leaving the disabled vehicle in a position prohibited by this section.
(3) A police officer, under authority granted by ORS 810.430, may move or require to be moved a vehicle that is parked in violation of this section.
(4) It is an affirmative defense to a prosecution of the owner of a vehicle under subsection (1)(b) of this section that the use of the vehicle was not authorized by the owner, either expressly or by implication.
(5) The offense described in this section, improperly positioning a parallel parked vehicle, is a Class D traffic violation. [1983 c.338 §671; 1987 c.687 §5]
The most common ways to run afoul of these sections is to be parked too far from the curb, or parked facing the wrong direction.