If you have the camcorder connected via firewire, when you open HDVSplit it should automatically detect the camcorder and identify it correctly as a Canon HV20... After that it is simply a matter of assigning it a folder on your computer for the capture and assigning a name. You can also choose whether or not to let it have a preview window. Then you just press the red Record button and the tape should play and the capture commence.
When it is finished, you open one of your versions of VS and then right click in either the timeline or library window and select Insert Media. Then in the dialogue box which will appear, navigate to the folder where you captured the video, and select the clips you want. I usually select them all. I also first set up a new folder in the library for that project's clips. The program will possibly take some time to think about all this, so be patient. Then it will begin to insert the clips. Once there, save the project and begin editing.
I always make sure I save the project very regularly in case there is a crash -- that that is now rare for me in more recent versions of VS. I have learnt over the years that crashes were often caused by my being impatient. When the program seemed to have stopped working, I would start clicking buttons and then it really would freeze and have to be turned off through Task Manager. But if I was patient and let the program work at its own pace, then things would eventually work without crashing. So patience really can be necessary and useful... Go make a cup of coffee and when you come back, things should be fine...