Not easy, I know.
Can you access this: American literature - Wikipedia, the free encyclopedia
This might also give you good sites to look into: American Literature Sites
Equally, for British literature: British literature - Wikipedia, the free encyclopedia
This is a fairly simple outline: British Literature Timeline
And this is another place to find other sites: Google Directory - Arts*>*Literature*>*World*Literature*>*British
Come back if there is anything specific you need to know.