How to lock the mobile phone using the power button?

How to lock the mobile phone using the power button?
By Mohsin Siddique

When you finish using the mobile phone, by clicking the power button you can close the phone and by clicking the middle button you can switch on the phone. By opening the lock, by pressing it to the right side the mobile phone would unlock.
The phone can be kept on the silent mode by clicking the lock button to the left side and by repeating it , the phone would be set on loud.