Your Archos Saphir 50 features a microSD memory card slot. If your personal computer has a slot for that type of card (Most laptop computers are so-equipped), you should be able to save music files
The Archos 50 Saphir is an Android phone and there are plenty of free ringtone apps such as MP3 Cutter, Myxer and more.
Here is a sample of the free ringtones (Archos 50 Saphir-compatible) offered here at MartinsRingtones.com:
Free Horror MIDI Ringtones Free Ghost Ringtones Free Short Ringtones Free Techno Ringtones Listen To All Our Free Polyphonic Ringtones