First you need to find it. It's probably in the folder Windows\System32 but not necessarily.
Open Windows Explorer, double-click the C drive, then hold down Ctrl and hit F
Enter *.scr where it asks for All or part of the file name.
Look through the list of found files for something relating fish and/or tanks.
When you find it drag it onto the flash drive.
On his machine drag it from the flash drive to the corresponding location on his machine.
"also there are other programmes i would like to copy - is their a way - please help - thanks "
Not really - most programs cannot be simply copied from one machine to another, they need to be installed using the CD on which they were supplied (or the downloaded installer, if they were downloaded from the net).
Of course, the above will only work if his Netbook is running Windows - some Netbooks run Linux.