A buddy of mine sent me a CD with some stuff he did. It sounds OK, but really needs some juice to fatten up the sound. Is there a way to do this in Sonar?
 
I pulled a song onto a track and cloned it. On the one track I beefed up the low end. On the other, I concentrated on the high end, looking for some crisp highs. It really didn't do what I expected. Any recommendations?

Well the short answer is yes, you can absolutely master in Sonar.  I do it all the time.  The deeper answer has to do with your knowledge of the tools at hand.  There are enough tools in the packaged version of Platinum to master a song effectively. 

Often the issue is just plain old loudness. I've fixed many wimpy sounding home grown efforts by simply running them though a process to bring the average RMS level up to what is more the excepted normal level . -12-14 db average RMS is a good benchmark for Rock and country.
But a multi band compressor is a good start. I know there's a new one I haven't tried yet that replaced the LP 64 multi band.

  Not to start a thirty page argument here, but this sounds like a chance to check out that L&R thing so many were bent out of shape about.
   SPLAT has the tools to do what you want to do, but mastering a mix takes practice. Mastering takes professional dedication. Of course the only way to get any experience is to do it. So...
   The new LP Multi-band compressor is a fantastic tool. You certainly can do the job with it. Just try not to get too heavy handed. The LPEQ is also very nice (I'm tempted to use all 20 bands on something just to do it).
   The CD your friend gave you is an opportunity to learn a new skill. Dive in the deep end and swim.

The new mastering plugins were built for you! Have a look at the CakeTV video below about them, and make sure you have this month's update of the engineering FX installed with the latest fixes. They are really very good and designed for exactly what you are trying to do. The video is an excellent summary of how to use them.
 
https://www.youtube.com/watch?v=qyqNJhSUGfI
 

Just for something quick and easy...try putting the VC 64 plug on the master bus....select the Master Mix preset from the pull down menu and see what it sounds like...you can tweek the settings in there too...might be a place to start
It adds some EQ and compression
 

I'm far from a mastering engineer (I'm far from an engineer at anything to be fair) but I mastered my recent album in Sonar and it is absolutely capable of decent results. It is probably capable of GREAT results if you have the knowledge.

Mastering has always been seen as a bit of a dark art but from my basic understanding and experimentation I usually end up with Compression, Multi-Band Compression, 'Character' or tone shaping EQ, Mid-Side EQ (for increasing width and centralizing kick drum etc) and limiting.
 
Real mastering engineers will do the same but usually (again in my experience) they will run lots of processors or hardware but only make very subtle adjustments on each rather than drastic adjustments on just one or two pieces.

I know that LANDR seems to spark controversy here but have you tried their demo? That may be all that track needs. I don't personally use LANDR, I use Ozone. Have fun mastering!

What is LANDR? I see it on my computer but never knew it was part of Sonar.

LANDR is an automated mastering service