Welcome to Nokia Support Discussions! Here you can share advice and tips with thousands of other Nokia users around the world in English. Many Nokia employees also follow and participate in the discussions, see our guidelines for more information. Everyone can search and read the discussions, but to post your own question or reply to others, simply sign in with your Nokia account. If this is your first time here, you can choose an alias to represent you. And if you don't have a Nokia account yet, please register.
The 6230i does not have support for Microsoft Windows Media Audio (WMA). You have to find a converter application to change the audio file format to MP3. Off the top of my head I don't know of any WMA to MP3 converters, but try searching using your favourite Internet search engine.
And look into Nokia PC Suite (http://www.nokia.com/pcsuite) for connecting your phone with your PC using Bluetooth. With its "Phone Browser" you get the phone's memory card directly visible in Windows Explorer and you can copy or drag&drop MP3 files to the phone's memory card for listening on the phone.