You can find the y-intercept by looking at the graph and seeing which point crosses the y axis. This point will always have an x coordinate of zero. This is another way to find the y-intercept, if you know the equation, the y-intercept is the solution to the equation when x = 0.
Remember that the slope of a line never changes, so you can choose whatever 2 points you want and you will always get the same slope. Calculate the rise and run (You can draw it on the graph if it helps).