#activate the package
library(ggplot2)

#load the dataframe
ID <- 1:200
values <- rnorm(200, mean=65, sd=15)
my.dataframe <- data.frame(ID, values)

#combined chart with ggplot()
ggplot(my.dataframe, aes(x = values)) +
  geom_histogram(aes(y = ..density..), binwidth = 5, fill = "grey") +
  geom_density(alpha = .2) 

#combined chart w/colors with ggplot()
ggplot(my.dataframe, aes(x = values)) +
  geom_histogram(aes(y = ..density..), binwidth = 5, colour= "black", fill = "white") +
  geom_density(fill="red", alpha = .2) 

#combined chart with ggplot()
qplot(values, data = my.dataframe, binwidth = 5, geom = "histogram",
      y = ..density.., fill = I("grey")) +
  stat_density(geom = "line", fill="red", alpha=.5)