I am beginner in development of 3-tired applications, so I need some help.

I am wondering if I have figured it right as I have to.
When I create some business logic, I create it in a non-visual class which I put on some interface (form). Then I call from form that business object (which return some value from data object) from some control inside form class in a way that business object return value for that form.

For example, from textbox I call line:
This.Value = this.parent.BusinessObject()
and
BusinessObject() contain line:
Return SomeValue.

Did I get this right, am I implementing 3-tiered development in right way as I have described?