pls how do i master the alt+tab???

I guess it depends on what you want to do with it.

The Alt-Tab combination will allow you to switch between open programs in Windows. When you hold down the Alt key and press the Tab key, a list of open programs will display.

Keep holding the Alt key and press the Tab key until the program you want to use is highlighted.

When you release both the Alt and Tab keys, the highlighted program will be active on your monitor.