I'm going through the session drummer tutorial videos based on an older version of Sonar, and in those it showed to left click on the track separator region to add extra track layers, but I've tried this as well as clicking through every tab and menu option in the tracks area and cant find it. I've been completely stuck with this for several hours now to the point of my brain getting completely fried.

When you first show take lanes, you get one lane by default. Each lane has a + button at the left that will add another lane above it. You can also right-click the layer to get a context menu with Add Layer, but the active area is small.