Point Slope Form looks like this:

First, we need to find the m value, or slope. We can do this by using this equation:

4 - 8 / 4 + 4 = -4/8 = -1/2
m = -1/2
Now, select one of the coordinate points, input those values and m, and solve for b.
4 = -1/2(4) + b
4 = -2 + b
Add 2 to both sides.
6 = b
y = -1/2x + 6
Now, input any number for x (I prefer 0, the y-intercept), and solve for y.
y = -1/2(0) + 6
y = 6
(0, 6)
After doing that, you can input that coordinate point into Point-Slope Form.
y - 6 = -1/2(x - 0)