Hi! i found the vertex for this problem, but how would i find the rest of the equation?

If you're working with focus and directrix, you know the equation of the quadratic is
.. y = 1/(4p)*(x -h)^2 +k
where p is the distance from focus to vertex or half the distance from focus to directrix. P is positive when the focus is above the directrix, as here. Of course, (h, k) is the vertex.

Selection (4) is appropriate.