Draw a set of coordinate axes with an x-axis and a y-axis.
For c = -6:
Plot the y-intercept at (0, -6).
Since the slope is 1, from (0, -6), move right 1 unit and up 1 unit to plot another point at (1, -5).
Draw a straight line through these points extending in both directions.
For c = -2:
Plot the y-intercept at (0, -2).
From (0, -2), move right 1 unit and up 1 unit to plot another point at (1, -1).
Draw a straight line through these points extending in both directions.
For c = 2:
Plot the y-intercept at (0, 2).
From (0, 2), move right 1 unit and up 1 unit to plot another point at (1, 3).
Draw a straight line through these points extending in both directions.
For c = 6:
Plot the y-intercept at (0, 6).
From (0, 6), move right 1 unit and up 1 unit to plot another point at (1, 7).
Draw a straight line through these points extending in both directions.
Each of these lines will be parallel to one another because they all have the same slope of 1. The only difference between them is their vertical position on the graph, which is determined by the value of c. If you use a graphing tool, simply input the equations y = x - 6, y = x - 2, y = x + 2, and y = x + 6 to see the lines plotted on the same set of axes.