Minecraft does not start

when I press the button "Play" seems to be loading then it close and reopen giving me this error: "Errore: impossibile trovare o caricare la classe principale net.minecraft.client.main.Main
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release
", sorry if it's in Italian. Please help me

My version of java is: 1.8.0_66