Using IFrame

HI

Can any body Explain

1. Why and how to use IFrame UI of WebDynpro

as I know we need to keep our HTML in src>mimes>components>OurPackage>OurHTML of our WebDynpro Project

but,

2. In the source property of IFrame how to give URL

3. How to get the inputs from input fields of that HTML to apply some logic

Regards

Abhijith YS