Why is hot, soapy water good for washing clothes? Let me copy and paste the statements from the book, which I failed to understand.
To wash clothing thoroughly, water must be forced through the tiny spaces between the fibers (Fig. 12.16). This requires increasing the surface area of the water, which is difficult to achieve because of surface tension. The job is made easier by increasing the temperature of the water and adding soap, both of which decrease the surface tension.
A help or hint will be welcome. Why do we need to increase the surface area of water if we want to force it through the holes of the fibre? Shouldn't we need to decrease the surface area?
I am totally confused regarding this point of the text.
 A: The increased surface area includes the sidewalls of the opening in the fabric. If you think of the spaces between the fibers as holes you could think of each hold being a very short capillary tube. You have surface tension of the water, and you have an adhesion force to the sides of the capillary tube. decreasing the surface tension increases the capillary action. If it was a long tube, this would mean that the water would rise higher in a vertical capillary. In your case lowering the surface tension means the water more easily passes through the small spaces between the fibers.
Note that it is a little more complicated when you think about the fibers being hydrophobic or hydrophilic. If the fibers are hydrophobic then the water will tend to bead up due to the surface tension and it will be harder to force the water through the small spaces between the fibers. But thinking about the the tradeoffs between surface tension and adhesion  if the material is really hydrophobic, the adhesion between the water and the material is really small and not much capillary action.
