Check out one of AE's particle effects. You'll probably find a tutorial someplace describing how to create smoke with one of them. Check out Videocopilot... or even the links to AE tutorials found within this document.
There are a bunch of ways to create smoke. Particle World, Fractal Noise, feathered masks, blend modes, but there isn't a button that you click that creates smoke from nothing. You've got to learn at least the basics and follow some procedures. The closes you'll get to smoke in a single click is one of the animation presets. They're not very convincing, both use fractal noise, neither are transparent, but you can fix all that if you know the basics.
It would also know what kind of smoke you are looking to generate. Smoke drifting through the woods after a forest fire is a whole different problem than smoke from a campfire, is a whole different problem than smoke from an explosion, is a whole different problem than smoke form spinning tires.
Unless the YouTube tutorials come from a reliable source -- Red Giant Software would be one among a few -- those things are hit-and-miss in terms of quality. For example, I wouldn't waste my time on any tutorial done by someone with a handle like "VideoBunny211". Hence the reason I pointed you to a page with links to trustworthy stuff.