So I got back into RollerCoaster Tycoon, and I've completed Forest Frontiers, Dynamite Dunes, and Leafy Lake so far, which are all get X guests by the end of X month and year with a rating of X. I've reached Diamond Heights, which is one of the ones that requires you to have a park value of X by X month and year. How exactly do you raise your park value?
Just make rides and stalls and whatnot. Make sure customers are satisfied. Just build a park pretty much.