Don't know about a tutorial, but I can try to put it plainly.
The game outputs telemetry that can be used to produce haptic feedback.
Haptic feedback can be delivered mainly in two different ways:
A massage cushion, such as the JetSeat
A tactile transducer (or "bass shaker", essentially a subwoofer), such as the ButtKicker
In order to produce haptic feedback based on the telemetry from the game, an interface is required; that's what SimShaker is. SimShaker transforms the telemetry data into something the haptic feedback devices can use.
If you use the JetSeat:
You need no additional hardware. Since it connects via USB, SimShaker controls it directly.
If you use tactile transducers/bass shakers:
Since they are regular speakers, SimShaker controls them by producing regular sound signals.
This means that you need a regular (analog) sound output device dedicated to SimShaker - be it a sound card integrated onto the motherboard, a dedicated internal sound card, or an external USB sound card - to which the sound signal can be sent.
You will also need one or more (depending on how many bass shakers you plan to use) amplifiers to drive the bass shakers, because a sound card does not provide enough power to drive them in its own.
SimShaker lets you decide to which sound device the signals will be sent.
SimShaker sends sound signals on the same outputs that you connect your speakers or headphones, why you can't use the same sound device for it.
If you have a free analog sound output device - maybe because you use some digital output, such as USB or HDMI - you can use that for SimShaker, and do not need to buy an additional sound card.
If you only have the onboard sound card, and you use that for your speakers or headphones, you do need to buy an additional sound card.
As you can see, there is a lot more to take into consideration when going for bass shakers, compared to JetSeat.
Hopefully it helps someone.