Press Command+Space on your keyboard and the spotlight search bar will appear in the upper right hand corner of your computer screen.
Start typing to search for an app, document, image or file and your results will start to autocomplete the search field with suggestions:
Example: Searching for Safari
Select your choice with your mouse or by pressing the down and up arrows on your keyboard and the press return key to open your desired app or document.
If you select a document or image, a “Quick Look” version will appear to the left of the column so you can see if you are opening the correct file.
To take a “Quick Look” at a file without launching the application:
Highlight your file and press the Space Bar on your keyboard
Additionally, you can press the down and up arrows on your keyboard to browse files and folders in a via “Quick Look”.