Help pls, installing Flash player update on Aspire One?

Hi, I got my daughter an Aspire One for Xmas (not brand new, it was originally bought in 2008) and never having had any contact with a Linux machine before I'm having a really hard time of things

From initial googling I'm pretty sure this machine is running Linux Linpus Lite, Xfce 4 Desktop.

Ok, so I set up the wifi settings with no problems, and my daughter is on the internet browsing away using Firefox. She wants to go onto a game site she normally uses, but it requires updating Adobe Flash Player from V9 to V10. The update is downloaded and needs to be extracted, I can extract to downloads or my documents, but not to the Mozilla/Plugins folder where it needs to be. Extractor was asking for the root password, and as I got the netbook from ebay, I didn't have the password. Solution, use the recovery disc to reinstall the OS and put in my own root password, which I have done. Now comes the problem......

Since reinstalling the OS, when I try to extract the Flash Player update to the Mozilla/Plugins folder, it comes up with the message "Not Allowed", it does not ask me for the root password (which I now have) any more. I have tried to manually copy/paste the update file from the download folder into the Plugins folder, I can right click and copy the file, but when I open the Plugins folder, there is no option to paste the file into there.

After more googling, I found a move file command I could use to move the file from one folder to the other, but this required me to type in the full location of the file, mv root/<username>/my documents/<file name> ect. then the destination folder in the Terminal, problem with this is, I do not know my username, when reinstalling the OS I don't recall it ever asking me to choose a username, and cannot find anywhere what username I am logged on as.

I have performed the mod/hack which means I can right click on the desktop and access the Terminal window, and a miriad of other stuff, but is there not just a simple way that I can log in as admin and perform routine tasks such as installing updates?

At the moment I have package manager open, and I can see that Flash Player 9 for Firefox is installed, but can't see a way of updating this to Flash Player 10.

Any help will be greatfully appreciated. I have used Windoze for years and years, and I am tempted to just install XP, but I am curious to find out about Linux, after many years of hearing it is a superior OS. Installing XP would feel like I have been defeated somehow, which I don't like, lol.