Now, this not exactly the way to password protect files on Mac. Infact, this is a way to encrypt your files on your Mac, which can be followed similarly to lock your files on Mac which could be opened when you enter right passwords.
We would using a small program called SecureFiles, which is an encrypting tool. By encrypting tool, it does not mean that it changes the type or format of the data that you are trying to lock.
So, what exactly this tool SecureFiles does. Well, it actually creates an image of the collection of all the files that you want to password protect on your Mac. And when someone tries to access that images, he requires the correct password to unlock them.
So, once to download, install and run SecureFiles on your Mac, simply drag and drop all the files that you want to set password into the space provided.
Now, you can enter the name that you want to give to the image that would be created. And once you are done with all the options like spotlight indexing, image size and image location, you need to click on the button labelled as Create.
That is it! This is how you can password protect files on Mac because whenever someone tries to access these files on Mac, he needs to enter the right password.