Windows 7, Movie Studio Plat 12, Sound Forge 10

I finally have some time today to try to follow the tutorial in the full user manual to get a handle on using Sound Forge, but a half hour of trying to get repeatability has passed unsuccessfully. I like keyboard shortcuts as much as possible; use Windows and Office applications professionally. I'm not entirely a newcomer to audio; periodic video editing and some audio editing over past 10 years in MS, Audacity, SF, but never time to work through audio procedures methodically.

I am on Manual pg 60 or so. I can basically edit the Voiceover; I can cascade the windows so that the Drumhit file opens in a separable window for dragging over to Voiceover. At first I couldn't drag at all; I now know that I have to drag up or down first. but the behavior of both L and R dragging and Alt+either one keeps changing, or so it seems. I am sometimes able to use drag after selecting all of Drumhit (Ctrl+A) to drag it into Voiceover and drop, inserting it. Other times, drag simply starts changing my selection (selecting less) or moving a blue rectangle the same size as the selection over it and opening a Mix/Replace dialogue to mix levels of the two files. (I never see the fades curves button mentioned in the manual, even if I select one of the fade presets.) I can't figure out what the variables of this most basic procedure are. What am I doing wrong, please?