This is a chart that explains the Trinity visually. I think it would be beneficial to understand the basic concepts of the Trinity before entering a discussion on their roles in salvation. The Trinity, as Martin-Lloyd Jones describes it, "is the differentiating doctrine of the Christian faith" (This quote is also at the bottom of the chart).
If you read some of the creeds and confessions from throughout church history, you will notice that they do not seek to explain the Trinity. They just affirm what Scripture says and leave it there. We must be careful that we do not seek to go further than what Scripture asserts.
This is a high and divine mystery! It is something that our finite, human minds cannot comprehend. Job 11:7 comes to mind as we consider this doctrine:
"Can you search out the deep things of God? Can you find out the limits of the Almighty?"
Courtesy of Tim Challies: http://www.challies.com/resources/visual-theology-the-trinity