Best Source For Helping Me Understand Existentialism

Doing research into Existentialism for a college paper. Have already done some reading, physical books and online sources. The biggest problem I seem to be facing at the moment is that the mere explanation of what Existentialism is could easily take up the minimum of 900 words. Further, I’m still not sure I have a handle on what it exactly is myself; I certainly don’t want to cut 'n paste. It’d be easier, but I truly want to understand; it’s why I chose this subject.

The basic plan I have for the paper is currently: 1) What is Philosophy, and how did it develop?; 2) What is Existentialism and how is it different from other philosophies?; 3) Where did Existentialism come from (how did it develop/what does it seek to answer that other philosophies don’t address?); and 4) How is Existentialism relevant or useful today?

Granted, that’s quite a lot; I think I could easily do better than 900 words on each of the above sections. I might need to narrow it down, but for now that’s the plan. What I’m really asking of you kind folks is the location of any online sites revolving around Existentialism that I can glean for information–the more I have, the better I understand and the better I can condense.

So please post any links to websites that are about Existentialism which you feel might help the layman (that’s me!) truly understand the subject. At this point, I can’t use links to books to be purchased or sought out at libraries; I’ve done quite a bit of that already.

If my request is now clear as mud, please don’t hesitate to ask for clarification, and I thank you one and all in advance for your assistance.