Can anyone suggest a tutorial on how to master a song in Sonar?  I don't have a ton of time.  I just need something that explains it as easy as possible.  I've looked at some videos, but I personally did not find them helpful.
 
Thanks!
Greg

you need a ton of time.
 

IMO, mastering is about the simplest use of a DAW there is, so the SONAR-specific part of your question isn't all that important.  Mastering is usually just a short series of FX inserts of the basic types: EQ, compression, saturation (maybe), and limiting (not necessarily in that order except for limiting being last).
 
I would suggest you not bother looking for a SONAR-specific tutorial and just look for a good mastering tutorial.  You didn't say if you were looking for a video tutorial.  If just a written tutorial works for you, track down Izotope's free guide to mastering.  It's Ozone-based but the information applies equally well to any virtual mastering rig.

Thanks, dmbaer!  I prefer a video, as I learn best by seeing, watching.  I'll check youtube.   
 
I do have a question, though.  After a track has been mixed down and exported, I know that to master it you have to then import it.   Do you add eq, compression, etc, to the Master bus or the track?  Or does it matter?
 
Thanks!
Greg

Bats Brew has a point in that time investment is required. If you "don't have a ton of time," then a third party is probably a better route to go.
 
The Mastering with Ozone 2015 that dmbaer mentioned is a good reference (found in iZotope's Educational Guides), but is not "short," and again takes time to read. That guide is definitely worth taking a gander at, since the tools can be replaced with whatever you have that does the same job. To answer your question above, EQ and limiting (compression) are used, but not to be confused with mixing (you are only using one track). The real goal at the mastering stage is to bring up levels to a target reference (often to a reference, and in-line with other tracks being mastered), polish stereo image/harmonics, and dither the result to the target media.
 
In its most rudimentary sense (if you have a good mix and one track only), the essence of things is a limiter and dithering. The biggest advice is if you feel the need to mix, then fix the mix first - do not attempt to mix here - and if time is truly crucial, a third party may be a better route.

There are also a few preset mastering chains in CbB that make use of the included plugins. Click on fx >+
 
You will wee a list. On that list are "fx chain presets". If you click on that you will see a "mastering" folder. These might get you close to something in terms of limiting and basic master. You are still free to adjust the fx in the chain to your liking. 
 
This is a good way to begin to understand the signal chains involved in mastering but as others have said, you will need to invest some time to learn it and get it right. 

First of all, thanks for everyone's input.  I appreciate it.  
 
By saying I don't have a ton of time, I meant per day.   I can spend time to go over things, but it will be over a long period of time.  I should have clarified myself on that.
 
I don't understand the mastering process because when I mix, I try to get it the way I want it to sound during the mixing process.  So I don't get why I then have to add more of what I already did to get it to sound different than what i already have and already like.   So I would like some kind of tutorial that I could go through to help me understand it all - and how to do it.
 
Thanks!
Greg

Starise
 
You will wee a list. 

Don't know if Tim meant "see a list" or "wee a little"...either one works. Either way, he's right about the inescapable time factor. Unfortunately, there's just no substitute for practice, practice, practice.
 
However, the iZotope guide mentioned above is a good place to start, regardless of what tools you end up using. And of all the possible routes you can take, I know of no quicker path for a beginner than Ozone. 
 
You're already taking the right approach by getting it sounding the way you want in the mix. Technically, mastering is an optional step, because it's possible to get there in the mix. The better the mix, the less "mastering" you'll need.

Thanks, bitflipper!  So many different ways to do it.  I just want something simple.   Someone also mentioned Wavelab Elements, saying it's pretty simple.   I'll also look into Ozone.
 
Thanks!
Greg 

Thanks for the link, mettelus!
 
Greg