I am not getting the hang of online documentation . I decided to change preferences to offline help, but the selection box is greyed-out in that advanced file preferences section. I searched my computer for sonar.chm file and it came up empty. Is there a source to download a pdf manual for sonar platinum? I have a lot of reading to do it seems

The local documentation is a separate installer available through the command center or from your account.

http://forum.cakewalk.com/Well-if-I-had-the-Manual-PDF-m3154557.aspx
 

To use online Help you have to be online at the time you want to use Help. The advantage of the this method is that you're dealing with the most recent help available. The offline documents aren't updated that frequently.
the Sonar Reference Guide is usually in Program Files/Cakewalk/Sonar Platinum folder.

If it's not there it could be in

C:/Users/Your user name/Appdata/Roaming/Cakewalk/Sonar Platinum folder.