Yes, I'm new. I've been using Sonar 3 for the past 14 years and just got Sonar Professional yesterday, and yes, I'm lost. But, I have watched the video on Addictive Drums, and I can't find them in Sonar.
 
Is there an easy ways to find them.

Did you install it? Here are the instructions http://www.cakewalk.com/Support/Knowledge-Base/2007013382/Addictive-Drums-2-Installation-Instructions
 

I did that. I went back to the XLN on-line installer and clicked on it again and it prompted me to reinstall. So, I must have it.

Do I need to register these?

You could check your XLN account to verify the your machine is setup to use the plug-in. If you are running Win10, some updates invalidate the authorization. To fix that you must remove your PC from your XLN account and re-register using the XLN installer.
 
You may also want to make sure the path to the Addictive Drums VST dll is in the SONAR VST scan path. I am not sure what XLN uses as the default path but unless you specified the default path used by SONAR, the VST install path probably is not in your scan path set up in SONAR Preferences > File > VST settings "VST Scan Paths."

OK - I changed from Windows 7 to Windows 10 and the next day changed Sonar from 3 to Professional. So, I've got some learning to do.
 
I'm used to using a VST adapter - I'm not sure how VST's get on Sonar Professional.

I checked XLN - looks like I'm set up ok - so it must be the path.

OK - so Sonar scans when you open it up. It says 49 plugins found.

MarkusClinus
 
I'm used to using a VST adapter...

Yeah, that's from quite a ways back....
 
Best to pause and take some time to get your bearings with Win 10 and Sonar Plat. 
 
You might want to look into "Classic Shell".  It's a free utility that makes Win 8 and later look like Win 7 and earlier.  It takes two minutes to install and setup, then after that, everything will look like Win 7 again. 
 
Then, at least, you'll only be confused with Sonar and not Windows! (For now. You'll learn your way again around Sonar soon enough -- but best to take it slow). 
 
For free training, there's YouTube, as well as CW's training vids.  For $15, you can buy a one-month sub to Groove3, and go through their Sonar Explained vids.

I think I'm doing ok on with Windows 10 - I just can't find Addictive Drums on my computer. I ran the XLN installer - registered my computer with XLN - but - no Addictive Drums. Obviously I missing something here.