how can I do this? can someone help me please?

@brunof56 Quite easily, but I don't know how to tell you. I will try to put together some links to useful software and educational reading..... Or Gilberto (woof) will beat me to it because I am going to bed.
David

Or Gilberto (woof) will beat me to it because I am going to bed.

No, I am not, I am also very tired today so I am off now. I will just direct the OP to the reacTIVision website, which is http://reactivision.sourceforge.net/ . That's the program and the external library you'll need to make it work.

Cheers to you two,
Gilberto