IVs and EVs are already explained in the FAQs section, but I'll do my best:
IVs are numbers that are added onto the basic max stats of a Pokemon. IVs range from between 0 and 31 (32 possible numbers), and there is an IV value for each of the six stats. IVs are decided for a Pokemon as soon as you battle them. So for example, a Dodrio (normal L100 speed = 205) with 14 IV in Speed has a Speed total of 219.
EVs are points that are added onto your Pokemon's stats. For every 4 EVs earned, one point is added on to your Pokemon's stat values. A Pokemon can earn a maximum of 510 EV points, and can earn a maximum of 255 EV in one stat (the six stats being HP, Attack, Defence, Speed, Special Attack, Special Defence).
EVs are earned by fighting specific Pokemon. Each Pokemon you battle gives you a number of EV (between 1 and 3) in one stat. For example, Whismur give you 1 EV in HP, while Spinda give you 1 EV in Special Attack.
For example, a Skarmory (normal L100 Defence = 285) with 21 IV in Defence, and 255 (the maximum) in Defence EV, has 285 + 21 + 255/4 = 306 + 63 = 369 Defence.
Hope you understand a bit clearer now