please tell me how to creta a countdown timer in visual basic

button1 (buton for start timer)
labelsec(Sec lab)
labelmin(min lab)
labelhr(hours lab)
txtsec(textbox for write sec)
txtmin(textbox for write min)
txthr(textbox for write hour)
please tell me how to programming

I don't think you got the point of showing what you've done so far / or have read the member rules.
Reverend Jim is asking for your source code, as this forum's goal is not to provide ready-made build-to-order programs, but help fellow programmers (by hobby, class or profession).
The second and most important reason would be to determine your level of knowledge.
It won't be much help if he asnwers put a timer and on every tick wait a second and then decrease your start variables by a second, if you are a total beginner. Or if you've used background worker and your problem is trying to cross threads it's a whole other approach.

I didn't download your project, as I'm guessing you've only placed 3 textboxes, 3 labels and 2 buttons and no code. If this isn't the case, I'm sorry. If it is try to use a timer see where that takes you.

commented: nice +3