A parabola opens upwards if its general equation is of the form x^2 = 4ay and sidewards if its general equation is of the form y^2 = 4ay.
For y^2 = 4ax, the vertex is (0,0). For any other vertex (x0, y0) the equation is of the form (y - y0)^2 = 4a(x - x0). So you can determine the vertex by seeing where the parabola intersects the axis. The focus is a point inside the parabola at a distance a from the vertex and lying on the axis.
The ends of the latus rectum are points of a chord drawn through the focus, parallel to the directrix which end on the parabola. For a parabola opening upward, they would have the same y-coordinate as the focus and the x-coordinate would be +2a and -2a.
For x^2 + 8y = 0 => x^2 = -8y=> a = -2
The parabola opens in the downwards direction. The vertex is (0,0). The focus is (0,-2) and the ends of the latus rectum are (4, -2) and (-4, -2).