When you speak to your pokemon ( eevee) is over lv 36 after every couple of battles with eevee 1st in you party speak to eevee and if a heart comes up in the little speech bubble Do a couple more without eevee fainted and speak to eevee again and if 2 heart come up this time, this means eevee his ready to evolve into Espeon or Umbreon. To get Espeon evolve eevee in day time & for Umbreon Evovle eevee at night time.... Just try it and see what happens