The Council shall have power to determine that the whole or any part of the expense of any public improvement shall be defrayed by special assessments upon the property especially benefitted and shall so declare by resolution. Such resolution shall state the estimated cost of the improvement, what proportion of the cost thereof shall be paid by special assessments, and what part, if any, shall be a general obligation of the city, the number of installments in which assessments may be paid, and shall designate the districts or land and premises upon which special assessment shall be levied.