The deck has to be mixed thoroughly before you can deal your first hand(s). Mixing up the cards is called "shuffling." When you play poker in a casino, there's a professional dealer to handle the shuffle, but at home, players take turns shuffling and dealing the hands . But not everyone can shuffle cards - maybe because they've never been taught or they never bothered to learn because it looks complicated. It's not.
Learning how to shuffle and practicing are key to mastering the shuffle. There are so many ways to shuffle, so try a few out and pick the one that feels most comfortable to you. I use a combination of the Riffle Shuffle and the Overhand Shuffle.
Here are some helpful video tutorials from Pokerology.com:
The Overhand Shuffle
The Hindu Shuffle
The Weave Shuffle
The Riffle Shuffle
The Table Riffle Shuffle
The Strip Shuffle