plotting graph
 

I'm a beginner using OpenFOAM.When I'm learning how to plot graphs as chapter 2.1.5.7 said, I can't get the figure as it showed in figure 2.11(velocity in x-direction vs distance from cavity base) in the user's guide. Do I have to use the sample utility?I don't quite understand what the part about the sample utility said!

You can use the sample utility if you want to make a plot using gnuplot. For a 2D plot in paraview, just use the foamCalc tool to get the components of the vector, and then plot as described in the manual.