ethanol is C₂H₅OH. to change it to ethene that is, C₂H₄. that is we have to remove the water molecule from etyl alcohol(the common name of ethanol).  the process is dehydration. it require sa catalyst in the form of concentrated sulphuric acid and a very high temperature.  

the reaction is C₂H₅OH -------> C₂H₄ + H₂O      i don't know about ethyne.

 good going.. once u get ethene by above steps ,brominate it using Br2 water and then perform dehydrohalogenation by NaNH2