if you pick a number and substitute it for x and then solve for y you will get a point on the graph. For example
if x=0
4-0=y
y=4
so your first point is 0,4
if x=1
4-1=y
3=y
second point is 1,3
if x=2
4-2=y
y=2
third point is 2,2
if x=3
4-3=y
y=1
fourth point is 3,1
if x=4
4-4=y
y=0
fifth point is 4,0
graph those and it looks like this.
Here is another view which shows the x and y axis and intercepts: