create a module - nice tutorials and directions

I want to create a module to send an email.

This is what module do.

Client enter her email address to a text box and save the email address by using a button from the front end (configuration page)

Business owner open up his view file, write an email and hit enter button.

Email go to the client.

Please see the attached diagram.

I tried to follow EE documentation’s “Module tutorial” http://ellislab.com/expressionengine/user-guide/development/module_tutorial.html

and “ExpressionEngine Modules” (http://ellislab.com/expressionengine/user-guide/development/modules.html)

But I cannot understand.

Can someone answer to these questions:

1. How should I separate my module requirements to relevant classes? eg: Get email address from the client - > What kind of class I need What functions should be there?

2. Are there any other tutorials somewhere in the web?

Thank you very much