Manchester-Boston Regional Airport (KMHT) will be the closest airport to the event. SOUTHWEST and AMERICAN Airlines fly into KMHT, however, prices may be higher than flying into the larger Boston Logan Intl. Airport (KBOS) in Boston MA.
Boston is the largest Airport in the region, with the cheapest and most abundant flight options available. Transportation North from Boston can be done via rental vehicle or the Boston Express bus. However, note that New Hampshire is not a particularly walkable state.