You can't learn about linear equations without learning about slope. The slope of a line is the steepness of the line. There are many ways to think about slope. Slope is the rise over the run, the change in 'y' over the change in 'x', or the gradient of a line. Check out this tutorial to learn about slope!
Got a bunch of data? Trying to figure out if there is a positive, negative, or no correlation? Draw a scatter plot! This tutorial takes you through the steps of creating a scatter plot, drawing a line-of-fit, and determining the correlation, if any. Take a look!