For me that's a very good explanation and I'll try to make some exercises and tests just to make sure I really understood... So for those of you that understand it very well, there are many people here that post some questions, like me, because they do not understand this kind of thing and do not have a programming experience then when you reply please put some examples... I have no problem to say I don't know and ask a question, but not all people do the same and they think they are bothering to ask again, You know what I mean... Besides there is a language barrier and not all people can express what they think or desire.
Thank very much Gramo and all I really apreciate your help.