Class properties - how to change values from form

[C# Programming]

Hi, this is my first posting at this forum and I need some help with my project. I am new to c# and still confused at times ...
My application is as follow:
I have main MDI_ParentForm, from which I open a ChildForm. I use ChildForm as drawing area for my graph.
I am dividing ChildForm up into smaller areas (rectangles). This is done by creating new object:

myDivisionClass myGDI = new myDivisionClass(this) ;
In my class definition for myDivisionClass I create object for each reactangle (for example: first rectangle represents grid area, second title, third labels for traces and so on ...)

myGraphGridClass myGrid = new myGraphGridClass(myRectangle);
myGraphTitle myTitle = new myGraphTitle(myRectangle);
myGraphLabels myTitle = new myGraphLabels(myRectangle);
etc...

Now I want to add a setup form (shown when pressing button on ChildForm), from which I could change properties of my myGrid object from myGraphGridClass.
I would also like to be able to open any number of ChildForms and change properties for each individual ChildForm object (so each could display graph with different settings ) ...

tnx, Pata