Please note: when tubes attached, you need to do all manually, and it is important that you use a lot of external light. If you don't do this in bright environment then you may have trouble to see the object through the viewfinder (too dark). More tubes you use, darker it will be.
There are some main steps how to use the tubes:
1) set your lens to maximum aperture (recommend);
2) set-up camera and lens to manual mode, switch off and detach the lens;
3) attach extension tube between the camera and lens (look for red dots and align on mount collars; attach same way as lens);
4) put your camera on tripod, or better on rail system;
5) put an object very close to the lens and use lot of light (1-3 flashguns, or 3x 500w lamps, or at least 1 strobe-light, or take pictures outside in bright sun);
6) if the photos is underexposed, please increase ISO and decrease shutter speed;
7) focus by moving camera further or closer (if on rail system), or use manual focus ring on lens mm by mm (very slow) until object in focus. If you use all set of tubes together, the focusing object usually need to be no more than 1 or few cm from the lens! Please remember that DOF (depth of field) is very small.
You don't need to use all tubes together - you can combine tubes - shorter length you use, in viewfinder becomes lighter, but again not as high magnification as with all tubes together.