You need to first mount your floppy. For this, go to the directory /mnt. Here, look for the name of the directory reserved for your floppy drive. It'll be either 'floppy', or 'fd0', or something starting with f. Now change your directory to something other than /mnt, or its child. At the prompt (if you are using GUI, you'll have to open a terminal), type
mount /mnt/floppy
(Here, 'floppy' is the name reserved for your floppy directory)
Now move to the dirctory where the file you want to copy is stored and type
cp filename /mnt/floppy/filename
(here, 'filename' is the name of the file to be copied into the floppy)
Your file is copied. You can move to the directory /mnt/floppy and open your file to view its contents. When you are over, move out of the /mnt directory and unmount your floppy by typing the following command at the prompt
umount /mnt/floppy
Now you can remove the floppy from its drive.
In case you are using a GUI, you can simply double click on the floppy icon on your desktop to open a window showing your floppy contents. You can copy your file from the source location, and paste it in this window. Close the window and thin right click on the floppy icon. A menu listing of commands will appear. Click on 'unmount' or 'eject' whichever is present in the menu.
