This is the tutorial on how to make a nether portal in minecraft pe.
PS: This works only in version - 0.12.1 and above.
Step 1: You Will Need
~>Flint and Steel.
Step 2: Base
For this you need to make a base of 4 obisidan blocks. Anywhere.
Step 3: Then,,,
On both the sides, raise the blocks to four blocks so that it becomes a rectangle of dimensions 5 × 4.
Step 4: Now,
Use flint and steel and tap on any obisidan block and it will light up.
Step 5: Jump!
Jump into the portal and whoosh! you are teleported!