How to solve think 4 ways quadratic equation.?

An Olympic diver is competing for a medal. His height in feet above the water can be modeled by the function f(x)= -3x^2+6x+24, where x is the time in seconds after he begins the dive. Graph the function. Then find out long it takes the diver to reach the water. 1)Write the function that represents the relationship between the height of the diver related to time. What does each variable represent? 2) What is a valid domain and range reflective of the problem situation? 3) When will the diver reach his maximun height? 4) How high will he be? i need to know this ASAP!