X-axis, Y-axis, the origin, and the four quadrants are all explained herein.
Plotting Points on X-Y Plane
This video explains how to graph points on the X-Y plane, as well as some common pitfalls to avoid.
The Four Quadrants of the X-Y Plane
This video explains the four quadrants -- I, II, III, and IV -- as well as a few things you're supposed to know about them, such as whether x- and y-coordinates are positive or negative in each of the four quadrants.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)