actually the help files have everything you need. Not sure if your version has the complete help tutorials but if it does this is defiantly the best place to start.
I figured Sonar out buy doing 3 things:
1; Open the program and and open a MIDI file from my collection.
Poke around and try and edit the file. When I ran into a problem,
2: Open the help files and use the search function for my problem.
3: Use the forum in 2 ways, Ask questions and make a habit of reading as many posts as you can while drinking your morning coffee or relaxing at the end of the day.
If your version is X1LE then go read the X series forum, most of your basic stuff is in X1.
Read back through this forum if your version is older. Or even read the older Producer and Studio forum posts, skim for questions that are the same as yours. 80% of the way things work is shared by all versions of Sonar. And all audio interface and computer set up is shard by all DAW users.
Most of what I know about Sonar can from just reading this forum and the help files. The rest was from just poking around in the program itself. Spend an hour exploring all the icons and menus. Open things up to see what they are for.
I could use the program within about a month, but it took almost a year to fully command it and be the one who then started answering questions.
Gear Slutz is another good forum for just reading and learning about audio related stuff.
Warning- don't believe everything you read.. learn to see what can be correct information.