A long procession accompanied a Maine National Guard tractor trailer hauling a 23 foot long by 3 foot wide steel beam from the World Trade Center. The truck arrived Saturday at the Freeport Public Safety Building.   After a short ceremony, it was taken away to be fabricated into a monument that will then be dedicated as part of a 3 day event Freeport is planning to commemorate the 10th Anniversary of 9-11-01 in the park at the Safety Building.