OK, since you posted this in the Cakewalk forum, I'll assume you are using Sonar or HS to do your multi-tracking. I'll also assume that you are recording in 24 bits - otherwise why the question?
Once you have finished doing your tracking and mixing, you are going to want to export a wave file from Sonar so that you can finalize it in Wavelab. Make sure you have the Apply Dither checkbox turned off in Sonar, and then File > Export leaving the bit depth set to 24.
Open the file in Wavelab and perform whatever finalization steps you need (eq, compressiuon, loudness maximizing, etc.). When the song is completed to your satisfaction, the bit depth needs to be reduced to 16 in order to burn it to CD. This is the very last thing you want to do to the file.
You can reduce the bit depth by simply changing it from 24 to 16. However, this simply chops off the extra 8 bits, and can leave the music with some unpleasant sounding artifacts. Therefore, when dropping the bit rate, it is usually wise to dither the file at the same time. Without getting too technical, dither simply adds shaped noise to the file in order to make the bit reduction more pleasant sounding to your ear.
In Wavelab, you have the Apogee dithering algorithm - which is purported to be quite good. Therefore, your final step should be to load the UV22 HR into the dithering module. Set it to 16 bits, and set the other parameters to get the best sound you can. Then "render" it.
This will dither it to 16 bits, but the file itself will still be 24 bits. IOW you'll have 16 bits in a 24 bit wrapper. Go to Edit > Audio Properties and change the bit resolution to 16. This is effectively truncating the file; however, it is OK at this point since you have already dithered it to 16 bits.
At this point I usually save the file under a new name (e.g., Song#12 - 16 Bit Mastered), however that is a personal preference. If you wish you can simply save it under the same name - although in doing so you will lose the original 24 bit file should you need to go back to it.
You are now ready to burn the 16 bit file to CD, using whatever software you wish. However, I can't imaging why you would want to use EZ CD, when you already have Wavelab.