The main reason of securing your disk is to avoid unauthorized access to data and files.
You may create a login password but that will not stop people like me from getting to your files.
So I want to show you how to secure your windows drive using Windows BitLocker encryption.
I assume that you partitioned your system already i.e you have more than one Local Drive.
Follow These steps:

Right-click on the drive you wish to lock and click on "Turn on BitLocker"

Then check the box before "Use a password to unlock the drive"

Then type in your desired password.

Thanks for the helpful guide. I recommend that everyone store their encryption keys securely so as not to lose access to their files. But if this happens, then EFS Recovery can help you. This is not a guarantee of getting access to files, but it increases your chances.