When it is deemed necessary to make a pubic improvement to be paid for in whole or in part by special assessment, the commission shall declare the necessity therefor by resolution, and such resolution shall state the method of assessment, the mode of payment and the number of annual installments. Such resolution shall be certified to the director of finance, who shall thereupon proceed to make an assessment report, in accordance with the method of assessment provided in the resolution, which report shall be filed with the commission and shall show the lots and lands assessed, and the amount of the assessment as to each, and the number of installments, not exceeding ten, in which such assessments shall be paid.