If you would like to start a new game in a new world on Minecraft Pocket Edition having a look around our site and finding an exciting seed would be the best place to start.
Once you find a seed that is going to take you to the exciting new world you need, you will need to know where to enter the seed.
Step one, home screen, hit ‘Play’
Step two, click ‘New’ to enter the new world
Step three, click ‘Advanced’ to get to the more advanced menu where you can enter the seed
Step four, in the Seed box enter the code that you have found. World type Infinite.
Hope this helps!