Your Link A2 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 Polaroid Link A2 is Bluetooth-enabled. Bluetooth is a wireless system which lets you connect your cell phone to other devices. If your computer is also Bluetooth-enabled, simply establish a connection between both devices and transfer your audio files from your computer to your Polaroid Link A2.
If these tricks do not work for you or if you prefer not to buy new accessories, you can always use one of the numerous free '3G Uploader' services available online. A search on Katapulco should retrieve plenty of them. 3G uploaders work as follows: Upload your own free ringtones on their web site and they will provide a temporary web address. Navigating to that URL with your Polaroid Link A2's browser will download the free ringtone.
Here is a sample of the free ringtones (Polaroid Link A2-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