Question: how to convert vbr to cbr?
Answer: Run MP3 VBR to MP3 CBR Converter Software.
Click "Add MP3 File(s)" button to add MP3 files. Then an open file dialog will appear, hold CTRL or SHIFT key to select multiple files. ... 
Set the bit rate as kilobits per second.
To start converting the selected files, click the "Start Converting" button.