Release the vice, remove the two pieces of the wire and release the two PCBs. Now place the 26-pin header in the holes just drilled. It should fit perfectly.
Drill all the required holes for the PCB. When done, carefully use very fine sand paper to smoothen the copper side of the PCB. Do not rub too much as the copper pads or tracks may get damaged.
Copper starts oxidising fast. So if you wish to store the PCB for a while, place it in a plastic zipper bag after applying transparent lacquer spray on the copper side. Before use, just wipe the lacquer with nail polish remover.