How to do??i don't want users can open alt+tab

How to do?? if i don't want users can open alt+tab and they can't see a name of programme on taskbar
(lock screen)

Why not? What kind of program are you making?

lock screen computer don't want no member use to computer

i don't want user put alt+tab for open other program and run taskbar manager for close program

The windows operating system has a built in lock workstation feature so I'm not seeing a good reason to write a program that locks someone out of their own computer.

In fact, I'm seeing a number of not so good reasons, so I would like you to explain the purpose behind the program that you are asking help for.

You can set the ShowInTaskbar property of a form to False and then it wont be displayed in the taskbar but why do you need to hijack the desktop from the user? If its restrictive like that no one will want to buy/install your program.

Hey, I would like to know how to lock my computer so my brother will not touch it.
A good enough reason for you?

Easy, set your Windows to have all users use a password in order to log on. No programming needed and its good enough for major businesses as well as home users. No need for anything else.

I've done something similar to this - but for a 3 attempts and you're kicked off sign on. That was more a practice of VB and API's though.

No doubt about it here - you want to use the Users control panel applet to apply restrictions in. There is also built in auditing (start > run > eventvwr and beneath the security tab) which you can use to see what the users have been upto which you simply wouldn't get with your app idea. Just simply give yourself a password and if neccessary disable any other user accounts on the system there or give them passwords also.

As suggested above, Windows has this functionality inbuilt & it's a tried and tested (and very powerful) way to accomplish your need.

Yes, i know this. But in VB its cool, so tell me a code in VB that makes it or
I will cry.

Wont really be possible anyways as the OS wont let you do it. You would need to write something in C++ in order to gain access to a low level OS kernal function.