Systray App - Need some help here

If you don't have .NET 2.0, then there are several other ways for your dialog box to obtain a reference to your main form. I've described one below

Define a public static readonly field in your main form (say Form1), like so:

public static readonly Form1 Reference;

Now change the constructor of Form1 to include a line to initialize the static field:

public Form1()
{
     Reference = this;
     InitializeComponent();
     // any other code
}  

It shouldn't matter that this is a static property because there will (presumably) only ever be one instance of the main form.

You can now call a method on Form1 from the dialog box with code like this:

Form1.Reference.SomeMethod();

To do this you have to use

dialogresult

to open the dialog use code like this:

MyDialog myDialog = new MyDialog();
if(myDialog.showDialog() == dialogresult.OK)
{
   this.someVar = myDialog.propertyValue; // get a property from the form and store it
   ...
   myDialog.Close();
}