This question is so general that a thorough answer would be quite long. Could you be more specific about what you want to know?
y = a(x-h)^2 + k is an equation for a parabola with vertex at (h,k). the graph opens up if a is + and down if a is -.
y = ax^2 + bx + c is another common form.
The y-intercept of the graph is (0,c). The graph opens up if a is + and down if a is -. The x-coordinate of the vertex is x = -b/(2a). Substitute that into the given function to calculate the associated y-value.
Again, what specifically would you like to learn?
