Growing pumpkins. need help.?

ok so me and my sister decided to grow pumpkins in an empty lot across the street were only weeds grow. we planted our first pack today and plan on doing the rest later in the week because its hard getting all of the weeds out. how well will the pumpkins grow in dirt that has a good amount of pebbles in it and the soil is probably very bad? and how much water should we water them? also we live in an area it starts to rain alot when the summer ends.