Could anyone give me a one or two paraghraphs on what were the reasons Byzantium fell to the Ottomans?

You mean Constantinople rite? or do you mean the Byzantine Empire?

Byzantiums walls fell to a newly invented supercannon, a siege cannon that broke down the powerful walls of Constatinople. There were also spies involved that opened gates, and that the Turks built tunnels into the city in order to get inside. Additionally, the Ottoman had superior numbers, time on their side and better quality troops.

Because the Ottomans were bigger, with larger population, a better organized state, while Byzantium was divided, impoverished, and had lost most of its territories and population.

I'd say mainly the resons above, plus that Byzantium was a corrupt, corpulent and decaying empire by then while the Ottomans were just atarting out with a burst of expansion energy.

No single event caused the fall of Constantinople. It was the result of the slow decline of the Byzantines and the rise of the Osman Empire.

Instead to elaborate on this topic, I suggest reading about "Manzikert", "Constantinople", "Osman" and "Mehmet" in Wikipedia.

Byzantiums walls fell to a newly invented supercannon, a siege cannon that broke down the powerful walls of Constatinople.
Who invented this cannon? The Ottomans?

The Sultan hired some Western cannon-makers, to make this cannon on the spot. This was how cannons were moved in those days; you melted down the metal and casted them at the seige-site.

The fall of Constantinople was a matter of time - the Ottomans controlled both sides of the Bosporus by then. The Byzantines were totally surrounded, isolated fr the West, had lost most of their traditional territories and faced with an expansive, confident, rising power.

When Constantinople fell, the Byzantines had already lost all of their asian territories and the ottomans already occuppied some areas in Europe. They were surrounded.

The decline of the Eastern Empire begun much earlier, when the Seljuk Turks went on gradually occupying all byzantine land in Anatolia. This proccess was somewhat reverted after the First Crusade, when the Empira regained controll of some lands. But shortly after the turks conquered them again.

I would say that what marked the final decline of the Byzantines was the 5th Crusade, when the Crusader troops captured Constantinople, that was believed to be invulnerable. They sacked the city and also occupied Greece, the two most important regions of the Empire. Even after the Crusaders left, the Byzantines remained severilly weakened.