Own portal

Hey!
What do you mean "portal"?
Do you have an example?
 
In survival? In creative? What version? With Command Block?
 
What version of the game? Do you would just a "teleporter" (a block or a button for example) or a real portal like nether portal?
 
So it's not really possible to use the Nether Portal to teleport you other place than Nether (It's hardcoded in the game).
You can use End Gateway however.
 
no i don't want to use the nether portal, but just make a portal look like portal nether then it will teleport me in another location
 
Okay, so you can do your structure and place a block at a certain layer wich you dont use in your map (structure void for example), and when the player has this block at the layer under (~ 5 ~ for example), you teleport the player at the new position. If that's all right with you, I'll describe the process in more detail.