I can't install Flash on Ubuntu 13.04

I'm installing Lubuntu 13.04 (updated really) and I'm having trouble installing Flash. I had trouble with the previous version too. I managed by doing all the updates I possibly could find! Well now I'm completely updated. I saw some directions for a couple of commands to enter at a terminal, but it told me that I don't have the rights, can't unlock a folder. I'm the only one on my netbook.

Any and all help is most appreciated. I'm terribly sorry if I didn't follow some procedure on asking.

To install Adobe Flash Player in Ubuntu 13.04, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo apt-get install flashplugin-installer