In order for you to enter an End Portal you need to find it located in a Stronghold within your world you will need a maximum of 12 Eyes of Ender to open the portal but all of them may not be required. To create an Eye of Ender it is an Ender Pearl (Dropped by Endermen) Blaze Powder so you will have to kill Blazes Located in a Nether Stronghold so go prepared. If you would like to do this in you world press LT with an Eye of Ender and it will float off in the direction of your Ender Portal but this can cause the Eyes to explode and dissapear.
On the other hand you can do it in the tutorial world where the Portal is at the co-ordinates:
Assuming that the portal is in the same place for everyone. When you reach the portal Ender Eyes in hand place them in each of the frames. The portal will now fill in and you can jump in where you will be transported into The End.