The path to your controller that you want to process the form should be in the action attribute of the form tag
<form action="[path to controller]">
In your controller, you want to use the Input Class to retrieve your form submitted data
$name = $this->input->post('name');
$name = $this->input->get('name');
//Depending on how you set your form up to send the data.
If you want CodeIgniter to handle validating your form submitted data, take a look at the Form Validation Class.