simple, /mb [block you want the portal to be] /goto [map name]
if you want a portal that tps you to another location in the same map, then just do /portal [block you want the portal to be] then add an entry block and an exit block
entry blocks is the block u have to click that tps you to the other location, which is the exit block
also you can make them air blocks if you want, so instead of people clicking the block to get tped by the portals or the mb blocks, they can just collide with the air block to get tped
