A substituted hydrocarbon is a hydrocarbon with one or more of the hydrogen is substituted with another element, (often a halogen such as chlorine or bromine) or another group of atoms such as -OH. Examples: -

a simple hydrocarbon is methane CH4. Substitute chlorine for hydrogen to get

CH3Cl Methyl Chloride is used for cleaning. Sub. Again to get

CH2Cl2 Methylene Chloride is used as paint stripper. Sub again to get

CHCl3 Chloroform is an ancient anesthetic. Sub again to get

CCl4 Carbon Tetrachloride is used in cleaning and fire extinguishers.

Substitute a single -OH group into -

CH4 to get CH3OH methanol or into C2H6 to get C2H5OH ethanol

The above examples all begin with unbranched non-cyclic hydrocarbons, but any hydrocarbon is a suitable target. A well-known instance is a double substitution of chlorine at opposite ends of a benzene ring to form paradichlorbenzene, commonly found hanging in toilet bowls. C6H6 becomes C6H4Cl2