This is one of those tips that is much easier to do than you might suspect. Early versions of Android made it easy to add an app icon/shortcut with a simple long press (tap and hold for a few seconds) on the home screen. The same goes for widgets as long pressing often yields contextual menus.
Android 4.0 Ice Cream Sandwich and later versions changed things up a bit by putting widgets in the app tray. Yes, the same place you go to find apps is now the spot where you’ll find a tab of widgets. Note that various handset makers will tweak the experience a bit and that your results may vary. In some case you might see Add to home screen or Apps and shortcuts, or something similar.
Another way to add something to your home screen is to open app tray (usually an icon that looks like small squares) at the bottom of your phone and scroll until you see the app, game, or widget that you want to put on your screen. Long press on the icon and drag it to your home screen, placing it where it feels right or fits best.