Follow these steps to lock your file :
1) Open any Ms office file.
2) Go to Save / Save as option.
3) Now Click on Tools option.
4) Now Click on General option.
5) Now Enter password to Open your file.
6) If you want to enter password for modify your file, You can also enter it.
7) Now click on Save.
To know more
FAQ
1. What is Folder short answer?
A folder is a storage space, or container, where many files can be placed into groups and organize the computer. A folder can also contain other folders. For many computer software applications, there is a current working directory. This is the folder that the application runs in.
2. What is folder computer?
A digital folder has the same purpose as a physical folder – to store documents. Computer folders can also store other types of files, such as applications, archives, scripts, and libraries.