The ordinance or resolution shall:
(a) Describe the land entitled to a special rate of taxation or the respective parcels of it if separate parcels are to be assessed.
(b) Fix the percentage of the regular rate of taxation which shall be applied in levying district taxes on the land described or on each parcel of it if various parcels are found to be entitled to different special rates in order that the taxes to be levied on this land will be proportionate with the benefits which it receives or will receive from the operations of the district.