You need to be in the folder where you want to conduct the search. You type the name of the file for which you want to search in the search dialogue box at the top right.
However, you can get to it the same way you did on previous versions of Windows by right-clicking on the Start Menu icon. Windows 10 has moved the File Explorer onto the Start Menu:
There are three distinct ways to search files on Windows: Keep reading to find out more about the changes.
Searching for files by name and by the contents of the files on Windows 10 is a bit different from Windows 8.