direction/inertia touch system (2d)

Hello,
I would like to create a direction/inertia touch system similar to " Desert golfing" for mobile devices.
The game I would like to develop will be similar to a Marble (toy) game.
If you touch the screen an arrow will appear below your finger( and this is really clever), moving from this point you will determine the inertia and direction of the shoot.( like worms or angry birds).
33412-desert.gif

You can see more info about this game her :

What will be the best option/logic to do that?
Thanks a lot for your help

Please use the tutorials that Unity and team created so you can learn these things. They actually created one speficially for an angry birds type of game. The control scheme applies directly to your question.

Making an angry birds style game

If that is too advanced, start from the top, Unity Learn