I'm from Belgium. My English is not that good, but I'm going to try to make myself clear

For my English exam, I have to analyse a poem. The poem is of John Keats, and it begins with 'A thing of beauty is a joy forever'.
Is there someone who has some information for me of the poem?
What does 'Endymion' means by the way?
Thanks for your help!!!
XXX
Marlies