If wikipedia confuses you on the God of War storyline, you should probably just shoot yourself in the face.
It's not a series known for it's complex story-telling, so the overall plot shouldn't be too hard to grasp.
God of War is about a man named Kratos who is in service to the gods so that he can be forgiven for the memories that haunt him. At one time Kratos was a general in the Spartan army, but they end up getting into a fight with the Barbarians. The Spartans have no chance of winning the battle, and just when Kratos is about to get killed he calls for Ares and offers him his life if he will kill his enemies. So Ares kills Kratos' enemies and permanently attaches the Blades of Chaos to Kratos' arms. One day the Spartans are destroying a village and the Oracle warns him not to go into a building, but he does not listen to her and he goes in there and starts to kill everybody in it. Unfortunately for him his wife and daughter were two of the people whom he killed. Then his wife and daughter's ashes are permanently attached to his skin. He later finds out that Ares was the one who made it so that he killed his wife and daughter. Back to the current time Kratos' is given one final job from the gods in which he must kill Ares. If he succeeds he will be forgiven for his past. His journey eventually leads him to Pandora's Box which is supposed to give him god-like powers. Ares kills him before he can open it though. Kratos then has to escape from Hades and make his way to Ares. Then Kratos opens Pandora's Box and kills Ares. Then when Kratos is about to kill himself Athena saves him and tells him that they need a new God of War. Kratos is the God of War for quite some time until one day Zeus betrays him and kills him. Kratos is saved by the titan Gaia though and then goes on a journey to find the Sisters of Fate so that he can change his past. He finally finds the sisters and kills them. Then he goes back in time and saves himself from being killed by Zeus. Kratos is about to kill Zeus when Athena stands in front of him and she is killed instead. Zeus then runs away, but Kratos is not finished yet. He then gathers up the titans and begins to ascend Mt. Olympus so that he can finally kill the gods. God of War 3 will explain what happens next.
God of War: Chains of Olympus is just a prequel explaining how and why Kratos had to give up his daughter forever both in life and death. He had to do this so that he could save the both the lving and dead people. So, he had to leave her to save her. There's a lot more to the story of this game, but that sums it up.
One lat question if you are so interested in knowing about the game's story why don't you just play through the games.
the clip sheet version
Kratos is a spartan who, to save his own life, made a deal with the the god of war Ares. while causin all sorts of chaos in his name Kratos kills his own family and is cursed to ware the ashes of his wife a daughter. Kratos kills Ares for revenge. afterwards he becomes the new god of war and still unhappy has sparta rage war on the cities of greece. Zeus, unhappy with this takes Kratos' powers away and kills him. Gaia mother to the Titans helps Kratos in is revenge against Zeus. Kratos discovers, after killing Athena, that he is the son of Zeus, and using time travel gathers the titans before there destruction brings them to help him destory the gods.
this is pretty much the story so far