First find the slope, m, of the line connecting these two points:
rise 3-(-3) 6
m = -------- = ----------- = ------- = 3
run -2-(-4) 2
Next, borrow the coordinates of one of the given point and substitute them, along with this slope, into the "point-slope" formula for a straight line:
y-3 = 3(x-(-2)), or y-3 = 3(x+2). This is the answer. If you wish you could solve this for y and obtain an equation in the form y=mx+b.