Open Sonar and open the project you want to work with. Use the View menu or click the shortcut to open the console view.
From the file menu, select "Insert," then "Stereo Bus." In the console view, you should see a track titled "Bus 1" to the right side of the virtual mixer. If you like, rename the track to "Master."
If it is not already visible, open the "Send" view by clicking the right-facing arrow icon in the menu to the left of the mixing console.
In the "Send" box in each track column, right-click and select "Insert Send," then "Master" (or whatever you named the bus track in Step 2). Click the power icon in the middle of each "Send" options menu to enable the send. As you do so, the audio in your project should become louder.
Once all of your tracks have a send enabled, your project is attached to the master fader. You can now solo the master fader and add effects, or simply mix the project as normal, paying attention to the peak meter on the master track. Make sure your project doesn't clip.