You have several options you can use to search a file. I will explain the easiest option here:
Using Search Box
You can type the full name or part of a file name in the search bar. Suppose, if you want to find a file with the name PRP, type the name and windows will attempt to find the best possible match. or If you want to find all the document files with an extension .docx, type *.docx in the search bar.