To select or activate something, touch it.
To type something, such as a name, password, or search terms, just touch were you want to type.
A keyboard pops up that lets you type into the field.
Other common gestures include:
Touch and Hold
To select a item, touch and hold it by not lifting your figure until something happens. This is how you access accent and other special characters on the keyboard.
Slide your finger to the accented letter you need
Touch, hold and drag
Touch and hold an item for a moment and then, without lifting your finger, move your finger on the screen until you reach the target position. You can move apps around on the Home Screen
Swipe or Slide
Quickly move your finger across the surface of the screen, without pausing when you first touch (so you don’t drag something instead). Slide a Home Screen left or right to view the other Home Screens
Double Tap
Tap quickly twice on a map or image to zoom in and out
Scale
In some apps (such as Maps, ChromeTM, and Photos), you can scale by placing two or more fingers on the screen at once and pinching them together (to enlarge scale) or spreading them apart (to reduce it)
Rotating the Screen
The orientation of most screens rotates with your device as you turn it. To keep your screen locked in Portrait Mode, swipe down with two fingers from the top of any screen and touch 
Portrait/Auto-Rotate in Quick Settings.