I dont know much about lore or the civil war but... What are the Stormcloaks and Imperials story? All i know is that the Stormcloaks want Skyrim to be free, but the Imperials dont want that. Can someone explain to me what both of them want?

The Imperials want Skyrim to remain part of the Empire. However, they made
a treaty with the High Elves that bans the worship of Talos, a god important to Nord culture.
The Stormcloaks are a rebellion that wants to free Skyrim so they can worship how they
see fit. They also have other issues with Imperials imposing on traditional Nordic culture.

Thats the jist of it, but there are other things you might want to consider. Some feel that
Ulfric Stormcloak is power hungry, and the rebellion is just a way for him to become
High King. Although many Imperials are sometimes arrogant in the game, Bethesda never really
shows you them treating the Nords badly at all. If you're looking for the side that's right, there
isn't one. Bethesda wanted the contreversy, but didn't put alot of effort into illustrating either/both
sides of the conflict. Unfortunatly, it makes the war sort of shallow and unrealistic.

Well, the Imperials are basically an ancient Empire of men in Tamriel, which at the height of it's power was the undisputed master of the continent. It was founded by Tiber Septim (Talos) who is revered as a god by the provinces of the Empire for this. Now, there is another great power in Tamriel, the Aldmeri Dominion which is basically a coalition of elves (Elyswyer and parts of Hammerfell are also under their control tpp). The head of this faction are the Thalmor whose power is intelligence and subterfuge. A build-up of great powers was bound to end in a war, which eventually happened and it was called the Great War. Due to very careful preparation, the Dominion caught the Empire (and their Nord and Redguard allies) off-guard and soon devastated the Imperial Army. They were so successful they managed to go all the way to the Imperial City, where they were defeated by smart Imperial tacticians. Both sides suffered very heavily, but the Empire was nearly destroyed. They signed a treaty called the White-Gold Concordant, which is heavily in favor of the Dominion and among many things, bans the worship of Talos. Understandably, the Empire's provinces (particularly the headstrong elf-hating Nords) were outraged by this and many lost all loyalty to this Empire, now deemed weak and pathetic by it's own people. The fact that the Empire now allows Thalmor Justiciar (essentially inquisitors) to freely roam within it's borders and execute and torture people on a whim, only added fuel to the fire. Enter Ulfric Stormcloak, a self-righteous Nord Jarl, who preaches his goal is to restore freedom to Skyrim and allow Talos-worship (he's essentially a William Wallace type of guy), and Nords flock like mad to his banner, forming the rebel faction Stormcloaks (named after Ulfric), whose first goal is to kick the Empire out of Skyrim and then face off against the Dominion. Now Ulfric isn't all roses as he's somewhat of a chauvinist and really doesn't care about anyone but the Nords (he only cares about himself according to some). Soon a civil war breaks out, but this only serves the Dominion as it weakens both rebels and Imperials. This is essentially the gist of it and I'm sure lore-masters could write pages about this topic.