Thank you chetan.apa for your answer.
I program in several languages, mainly .NET, PHP. But i make some projects in Java, Python and C. I have no problem to learn a new languaje.
About the techniques, I am sure that my data have any patron because for example if in april down the sales sure same month (April) of previous years too down the sales.
I think first i should make a descriptive analisys to understand the data. ¿Correct? later in function of the descriptive analisys result i take a decision for the next method
if the last paragraph is correct, ¿what need to start? i have seen something about R
Thank you