y = -x - 2.....in y = mx + b form, the m represents the slope and the b represents the y int. (and if u didnt already know, -x is the same as -1x)
so in ur equation, the slope is -1 and the y intercept is -2....or (0,-2)
so u would plot (0,-2) and use the slope of -1 to plot another point. Draw a line through the points.