There have been several recent posts about this, for example, this one.

Processing doesn't have any decent way of displaying graphs, so you're going to have to build your own from scratch:

If the data is not already loaded, you'll want to load it with loadStrings()...
Then, you'll have to use arrays and for loops to deal with the data...
And you'll probably want to display it with a bar graph (look at rectangles) or a line graph (look at lines).

Hopefully that will be enough to get you started...