To face the expansion of the coronavirus, our best weapon is a correct hand hygiene. So in this link, you can check out a document by the World Health Organization (WHO), in which it is clearly shown how to wash hands with water and soap in case of visible dirt and for how long we should be doing it, between 40 and 60 seconds.
If you have been exposed to a risk situation (coughing, sneezing, etc.) or you have no toilet around, the best way to disinfect your hands is to use an alcoholic solution. Find here a short video that shows how to do it.