This one is a hard one! Open up the game that has that nice jigsaw piece for an icon. That there is called "Microsoft Jigsaw". When you get into the game, and you're signed into Xbox Live, head into the Daily Challenges section and play any of the three challenges offered right there. You don't have to complete the challenge (I didn't at least), the Achievement should unlock as you're playing it.
And bam, you're done!
In all seriousness you will have to do a few hundred of these daily challenges for the following Achievements:
That being said, you should get used to how boring they get right away.