The graph is a straight line with this characteristics:
slope: the coefficient that accompanies the x variable, so it is 2.
x-axis intercept: find from y = 0 => 2x - 6 = 0 => x = 3
y - axis intercept: find from x = 0 => y = 2(0) - 6 = 6.
With that information you can draw you graph.
Just in case you need more information, you can build a table with several values of x and y:
x y = 2x - 6
-5 2(-5) - 6 = -16
-4 2(-4) - 6 = -14
-3 2(-3) - 6 = -12
-2 2(-2) - 6 = -10
-1 2(-1) - 6 = -8
0 2(0) - 6 = -6
1 2(1) - 6 = -4
2 -2
3 0
4 2
5 4
Now you have plenty information to draw the graph.
6 6