Help adding more than one item to graph

[jordelver]

Hi,
I've now managed to create a simple graph to monitor my HDD temps. I created a very simple bash script which gets the temp from the hddtemp program. This is assigned to a data source which takes one argument - the disk to monitor.

The problem is that I don't understand how to add more than one item to the graph. See the attached pic, it shows what I have so far.

How do I go about using multiple data sources on one graph?

Thanks for any pointers.
Cheers,
Jord