When you have an equation with two variables, it's easier to graph it in the form y=mx+b. b is the y-intercept - the x-value at which y is equal to zero, and m is the slope of the graph.
So if I have the equation 3x+2y=12, I have to first subtract 3x from both sides.
2y=-3x+12. Now I have to divide the whole thing by 2 to get my y value alone. y=-3/2x+6.
Now, to graph it, I have to first plot the point where y equals zero and x equals six. Then you plug in different numbers above and below this. When x=5, you get y=-3/2*5 + 6 which is -1.5. So you have the point (5, -1.5) and also the point (6, 0). You can plug in 0 for y and solve for x to find the x-intercept, or when x=0. 0=-3/2x+6. Subtract six from both sides. -6=-3/2x. Divide both sides by -3/2. 4=x. So you have another point - (4,0).
Now that you have three points, you can connect them with a line and add arrows to the end.
Hope I helped!