How may I discern and conquer Mara?

In fact I do not even know how to discern Mara and what is not Mara. A compulsive urge or something done of an impulse can be considered Mara right, but what else? This seems no different than the concept of the Devil in Christianity, who is an external being instead of an internal one. Ok, so say I get an urge of ual desire, what should I consider this? It is ual desire, but how may I stop acting on the urge? I feel torn between seeing it as a simple biological urge and seeing it as Mara and so should not be obeyed. It is a biological drive, but is it more? Should I stop it at .."it is a biological drive"? It is hard not to act on an urge of ual desire. By act I don't mean go out and have either. It could just be to go look at say...something on the internet. Any ideas on what to do when this urge overcomes me? I understand many people will say it's ok it's natural, but it seems like a problem for me. Maybe I am just misunderstanding something about what the Buddha says. Perhaps I am misunderstanding the Dharma. So I ask the Sangha. Well if there is something you don't understand about what I am saying please ask, so I may clarify. I don't know how else to put it.