According to the Minecraft Gamepedia, "The end gateway portal is created after defeating the ender dragon and is used to gain access to the surrounding islands containing chorus plants and end cities quicker than by other means."

If you want to know about the Minecraft 1.9 update, go here: http://minecraft.gamepedia.com/1.9

This design is pretty simple, so just glue 1:1, 2:2, 3:3, etc.