Select the BB Gen block from the list in the Settings Browser to display the Parameter View for that block.
On the General Settings tab, click the Waveform Source Name cell.
Click the Details
button 
that appears in the Waveform
Source Name setting cell to display the Open
File dialog box.
Navigate to the drive and folder that contains your waveform files.
Select the desired waveform file.
Double-click the file name or select the file, then click the Open button to replace the default waveform file displayed in the Waveform Table with your selected file.
Repeat steps 1 through 6 for each BB Gen block.
Click the Download
Panel button to return to the Waveform Setup Table.