1.get salt 2.get water3.pour salt into water4.stir the salt and water until the salt is invisible
It begins todissolve on contact with the water, but it is fully dissolved when you cannot see most individual particles of is a solution.
Depending on the substance, you can use organic solvents, acids, melting with fluxes and dissolution, dissolution under high pressure and temperature, etc.
Fats and oils.
Because water and salt are extremely polar substances, where as gasoline isn't. For information on polarity: en.wikipedia.org/wiki/Polarity