Hey Karen - you can make reservations online at the park's website (it's listed on this page too!) here: C.B. Smith Campground Website.

Hey there Karen, It's best to call the park office directly for reservations, especially if you'd like to stay longer than 7 days. The website only allows bookings up to 7 days. Calling them directly will give ya much longer stay options, up to 5 or 6 months long (I forget which). We stay there at least 4 months during the winters every year now.

I had to call the park directly, and they were very helpful to reserve a place for us.