Firstly start ScummVM by tapping it's icon on the springboard. You'll notice that not ScummVM itself will start but actually a 'Launcher' app, where you can decide if you want to start ScummVM itself, the FileManager or have a look at the First Aid. Now just start the FileManager by tapping it's icon.

You can leave the FileManager and go back to the launcher at any time tapping the 'Exit' button on the upper right. The FileManager is divided into 3 parts shown as tabs:

• Installed games
• Savegames
• ScummVM log

For now, we will only deal with the 'Installed games' tab as shown on the right. In your case the list is probably empty, but that's exactly what we want to change now!
If you tap the 'Edit' button on the upper left, you can delete existing game data or add new game data. So tap the 'Edit' button and then the newly shown line 'Download from FTP'.

In the Downloader you first have to tap the 'Choose directory on server..' button to select the directoy on the FTP server containing the game data files.

If you have a WiFi connection and a MacOS X machine on the local network with enabled file sharing service (System preferences -> Internet & Network -> Sharing) it will show up as Bonjour host in the server list. If you have another desktop system like AmigaOS, Windows or Linux you have to install and configure a FTP server. For example RC-FTPd (AmigaOS), Serv-U (Windows) or proftpd (Linux). In any case make sure you configured a user with enough access rights on the server for the game data directories.
Now tap the Bonjour host or 'Add new FTP server' and enter the details (username, password, hostname or IP, port) as needed in the upcoming dialogue. Another tap on the host will connect to the host and let you browse the directory tree.
Navigate to the directory containing the game data files, but do NOT enter it. Instead tap the green down-arrow on its right to choose it as download source.

Back in the downloader all you have left to do is to give the local directory a meaningfull name if needed and tap 'Start download'. The downloader will start generating a list of the files to download and then actually download them onto your device in the specified local directory. After the download finished, you can leave the downloader again with the 'Done' button on the upper right.

Now that we have our game data files on our nifty device, we can leave the FileManager by tapping the 'Exit' button on the upper right. Back in the Launcher we start the real ScummVM by tapping it's icon.

After the ScummVM home screen is shown, you can navigate it using the crosshair pointer which is moved with your finger like you would move a pointer on a notebook touchpad. Tapping equals a left mousebutton click.
Position the crosshair over the 'Add game' button, so that it will be lit and tap with your finger. In the upcoming directory browser you should see the directory we downloaded earlier named like you specified in step 5. Highlight it using the crosshair and select 'Choose' on the lower right.

If ScummVM knows the selected game you'll now see the game settings dialogue with everything set to reasonable default values. In most cases you don't need to change anything here and can just leave the dialogue with the 'Ok' button.

Now you're ready to start having some fun! So just select the game entry in ScummVM's home screen and hit 'Start'.