C# .NET - How to navigate to partiuclar page in help file in windows application?

Hi all,

I displayed a help file when the user press key "F1" in WINDOWS Application. So when the user press key "F1" it shows the user defined help file as separate form. This help file contains contents with navigation. If we click on the any one of them that navigate you to the target file. But that target file displayes with the same form.  The thing is when the user enter to the sub form of the main form and the user press key "F1" what happening is that will navigate to the targer file which is related to the sub form instead of showing up the main file. So How to navigate to particular page in help when the user press key "F1".

Thanks

R. Eswaran.