Finish your project, go to Tools - Mixdown Audio - Bounce to Track. Format: Mix to Single Track Stereo Events, uncheck Each Source to Separate Mix, hit OK. This will mixdown the audio and put it on a new track within your session. You will need to solo this track (to keep it from mixing with the previous tracks and adding greatly to the volume). Click the track to highlight it in black, and go to Edit - Audio - Normalize. This will look at the peaks and raise the volume of the entire track to make the peak at maximum level. Then, go to Tools - Mixdown Audio - Export to File and make your finished .wav file.