I'm struggling in math?

I'm a freshman and I'm really struggling in Algebra II. I've been catching up well in previous chapters, but now we're on the quadratics and I'm soooo confused... I don't really get how to get the y intercept, point of symmetry, and the vertex point from a quadratic equation. I was absent on the day we learned the vertex form and stuff, so just looking at it doesn't help. I don't know what to actually plug into the formula. Can someone please explain it to me?? :[