N.H. Rev. Stat. Ann. § 38-C:4

The compensation of the commissioners shall be fixed by the municipality. They shall be sworn to the faithful discharge of their duties. They shall annually organize by choosing one of their number as chairperson of the board. They shall appoint a clerk and a superintendent of public works and such other officers as they deem necessary. A certificate of such organization shall be filed with the clerk of the municipality. The commissioners shall fix the compensation of all officers and agents appointed by them. All officers and agents shall be sworn to the faithful discharge of their duties.