How do you create a portal that can be used with DoD teleport stones? I want to put one near the Rune spire above Hammer

I went to the map book and sucesfully created a map slot, but now what ? How do i place a portal ?

You can't just create a portal where you want. You can only set your portal to one already in the game, or set one to your personal house location. Your map will be automatically added to the white portals as those are the free default ones. You can then buy a Map Bind to attach your map to one of the black portals, or buy the House portal thing and build one outside of your house to attack your map to.