Download a free MP3 plug-n program to the computer's desktop. DOWNLOAD LINK
Double-click on the icon of the Audacity program to launch it. Select "Open" from the "File" menu at the top of the screen. Navigate in the window that appears to the WMA file
Click once on the WMA file with the mouse to highlight it. Click on the "Open" button on the window to load the WMA file into the Audacity program and close the window.
Wait as the Audacity program analyses the WMA file and displays it as a "wavelength" bar on the program's main screen.
Select "Export as MP3" from the drop-down menu beneath "File." Click on "OK" if a pop-up window asks to mix the audio track into stereo.
Select "Desktop" from the drop-down menu beneath the "Locations" tab at the top of the window that appears on the screen.
Name the MP3 file that is to be made from the WMA file in the "Save As" column at the extreme top of the screen.
Select "MP3 files" from the "Format" drop-down menu at the bottom of the screen. Click the "Save" button at the lower-right corner of the screen.
Delete or archive the WMA file once the MP3 file has been saved to the computer's desktop. Quit the Audacity program.