There are two efficient and accepted methods for graphing lines -- this is one of them.  For the other one, we'll need some more ammunition, so I'll save it for later.  You WILL need to master both.

On to method 1... First of all, you'll need to know what an intercept is!

the graph of a line through the x-intercept and the y-intercept...the x-intercept is where the line goes through the x-axis, and the y-intercept is where the line passes through the y-axis

The intercepts are where a graph crosses the x and y axes.

Not only are these the easiest points to find, as you'll see later in math, they are the most important points.

Here's how this works... Let's graph

3x - y = 6

Make an xy table:

a two column table with the left column for the x values of the two intercepts and the y column for the y values of the two intercepts 

Fill in 0's for the
x and y like this:

an xy table with 0 in the x axis for the x-intercept, and a 0 in the y column for the y-intercept