need help displaying plugin form within a page

Hi,

I am new to creating wordpress plugins and I need help to finish my first plugin. My plugin create

• Create a config options page under settings menu
• Allow user to save and modify plugin options
• Renders the contact form within a wordpress page

I can get my plugin to do the first 2 points above but I can’t get it to render the contact form within a wordpress page.

I want to allow users of my plugin to add a line to a wordpress page for example [greendesigner_contact_form] and when the page is rendered in a browser the [greendesigner_contact_form] part is replaced by a contact form.

Does anyone know how to do this?

Any help would be much appreciated.

Xander