Cant understand How MVC works in CodeIgniter...

[eluser]Unknown[/eluser]
Hi,
I have tried lots of time to understand MVC in CodeIgniter but I failed...

I just want to design a simple page in which view part contains 4 fields Named First Name,Last Name,Email etc...

And I want to check in controller that Email should be valid and all the fields must contain some value...

And I want store it in a database and want to check that Email should be Unique...

May be I can do controller but I dont Understand Model...

So any one can help me what should I do..???

Thanks in Advance..