Execute PDF file

I have created a textbox with a word in it. When I click with the mouse on it, I want to see a PDF-file in Adobe Acrobat Reader. Therefor Acrobat Reader has to start automaticly with the desired file.(Like Windows Explorer double click)
How can I do this?
Please give me some code
Thanks

use the ShellExecute API and pass the path to the PDF file as argument 3. This will start Acrobat reader if it is correctly installed.