[www.library.utoronto.ca]
might help you a bit further.
About Mattew Arnold:
[www.victorianweb.org]
You can also try to go to www.google.com and type his name between "..." and see what you can find on him.
As for an interpretation: the speaker is talking to a you. Is that person there? If not, is that person dead or somewhere else? Does the speaker feel positive about that person? Is the speaker happy?
Answer these questions and you'll be already halfway an interpretation. Then you can come back with more specific questions.
I'll give you a hint on the rhyme scheme: the first stanza is:
a
a
b
b