If it is Hell, I do not know..... But if it is Enderworld, you kill the boss (Enderdragon) and there will be a portal where he is dead. Go in it, and there will be some things, like a conversation. That is you "Player's name" Blah Blah Blah. You press Escape, It shuts off right away. You press >, it goes faster.
You can't make a portal to the end, you have to find a stronghold and find the portal in a stronghold. Then put eyes of ender in each of the missing slots. Then it will teleport you into the ender world. and to get out you must defeat the dragon of course
creative = spawn in ender blocks for portal then insert eyes of ender in each block survival= use eyes of ender by throwing them in the sky and following them to get to the stronghold where one will be