Before we install the terminal , we should tell Android that it should let us install app that is not coming from Play Store. At the moment , Play Store does not support terminals so you cannot find the app.
To tell Android that it should let us , navigate to Settings->Applications. Check the "Unknown sources" and agree if it asks you something.
Now we are ready to install the terminal. Press here
and download the file. Click it and install it.
Once it is installed , you should open the Terminal app. Type the word "su". It will ask you for root access , and you should give it so it has rights to run scripts (which we will later use to launch Ubuntu).
To properly test if your terminal and busybox libraries work , type "busybox arping --help". If it prints some text and you see lots of parameters like -f -q -b it is working. If not , check if your phone is rooted , check if busybox is properly installed and check if terminal has permissions.
If it is OK we can continue.