To open the file browser click the icon near the top of the left side menu here:
When you open the file browser you will see a screen like this with lots of folders, and not all of them are accessible:
Find the folder called "guest-data" this is the location to save files you would like to keep on the computer and be able to access again after your session ends. There are a couple ways to get to the folder, see them circled below:
Watch out for the "guest-prefs" folder or the other folders under the "Bookmarks" heading, these locations are not accessible (related to the user template the guest account is based on) hopefully sometime in the future we will figure out how to hide these folders.
If you saved a previously saved a file in the guest-data folder on another computer, but if you are not able to use that same computer again (for instance if it's already occupied by another user), you can navigate over the network to retrieve your file. In the file browser menu on the left side list of folders toward the bottom you will see a heading called Network, with a link for "Browse Network", click there:
For instance if you saved files on PC1 in a previous session (notice that all the computers have a label on the top of the monitor screen) click on the icon which says SOUPHUB-PC1 beneath it:
From there you will be able to copy or open your file. It's probably a good idea to copy it to the computer you are currently working on. You can click and drag it to the "guest-data" folder under the Bookmarks heading, or select the file you want to copy with a single click, then right click and select "Copy" to copy the file. Navigate to the directory you want to save it in, then right click again and select "Paste".