either click on new graphs in the top left, or add graphs for this host at the top of the device listing.
From memory it will then ask you the name of your ups, I left the settings pretty much at the default and the ups and cacti are on the same box so the name of my ups is just ups@localhost (pretty boring huh)..
I had to ditch the temperature graph as it doesn't appear to be monitored on my ups. Other than that it all works well. Some time down the track I can see myself putting them all on one graph as all the individual ones aren't needed. Just a matter of getting some time, but there hasn't been much of that spare recently.