Obtaining the permit is the first step. To begin the permit process you need to submit plans depicting the proposed improvements, submit a copy of the property survey with the improvements drawn on it and indicate the construction type to be used.
Don't be discouraged if this sounds complicated. Handouts are available to help you with each type of permit. You should be aware that once the plans are approved by the Construction Office you are required to build to match those plans. If changes occur during construction they must be made with the Construction Office's written approval.
The second step is the inspection of the work. The property owner is responsible for ensuring that inspections occur at specific times during construction. You may have the contractor call to schedule the inspections but please make sure that your contractor follows through.