welcome to the show
there is tons of info on the site already spend some time looking at old threads.
SPECIFIC spot locations will not be shared by most members as we have earned these from countless hours of fishing. there is plenty of access along rt 1a with all kinds of parking and structure.
go to amazon.com and buy yourself a book about surfcasting in new england there are a number of them. i am reading zeno haromins fishing with artificials and it is excellent
what kind of rods/reels, plugs (lures), tackle, etc. do you already have?
new hampshire is beautiful and there is plenty of sweet and salt water plenty close to each other.
you may not be use to the rocky coast line so i would suggest purchasing some korkers for your feet to help ensure a solid foot hold.