Follow the link in the Resources section to the "Free MP3 WMA Converter" website. Download and install the WMA conversion software.
Open the WMA conversion program. Click the "Output Format" button at the middle of the window. Select the "WMA" option from the drop-down menu.
Remove the check mark from the check box labeled "Save in the File's Directory." Click the "Output Path" button.
Find the folder where you want to save the converted WMA file and click its name. Click "OK." Click the "File" button at the top left corner of the window.
Select the "Add Files" option from the drop-down menu. Navigate to the M4a file you need to convert. Click the M4a file's name and click "Open."
Click the "Convert" icon at the lower left end of the window to convert the M4a file into the WMA format.