Thanks xvetox, the link you provided works good to me and the information is acceptable though not perfect.
I have found is not clear what to do with, example, ENA or ENB, say, if you do not need to declare it it your script.
Also, in the PDF you provided, the ARDUINO GND is connected to the L298N board GND. After some experimentation it seems not really needed, however, which is weird to me, if you turn OFF your L298N power supply, the board stills drains from the arduino, this is, if you do not like to see the 'direction leds' ON or worst blinking, seems to be needed to disconnect both the power supply AND the ARDUINO USB from your computer.
I like more the Brian Schmalz Easy and Big Easy Driver behaviour (based in Allegro A4988) though the problem of the absence of a heatsink which means is easy to blow the A4988 device if your stepper demands too much energy! (say, a transient over 2A which is the upper limit ....)
Anyway, thanks a lot.