The basic idea is that you assign ggplot2 plots to an object, and then use the arrange function to display two or more. Here's an example. First copy and paste the code above (or put in your Rprofile). Next install and/or load ggplot2 as described in a previous ggplot2 tutorial.
# Load the diamonds datasetAnd here's what you should get:
data(diamonds)
# Create a histogram, assign to "plot1"
plot1 <- qplot(price,data=diamonds,binwidth=1000)
# Create a scatterplot
plot2 <- qplot(carat,price,data=diamonds)
# Arrange and display the plots into a 2x1 grid
arrange_ggplot2(plot1,plot2,ncol=1)
...