To get started, read these tutorials: http://www.apedroid.com/android-applications/external-keyboard-helper/get-started
For information about the permissions it requires, go here: https://sites.google.com/a/apedroid.com/www/android-applications/external-keyboard-helper/faq
This is a crippled demo version of External Keyboard Helper Pro
Everything works just like in the Pro version except for the Space button which prints a message that this is a demo version.
The only reason to install this is if you want to try it out before deciding if you want to buy External Keyboard Helper Pro.
For more information read the description for External Keyboard Helper Pro.
NOTE: This demo version is sometimes rated bad by people who did not read this description and/or do not understand the idea of a free demo version. To get an idea what people really think about External Keyboard Helper you should take a look at the reviews for the Pro version.