Checkbox and Combobox

[Neiklot]

Hello,

First of all thanks by your admin is super!!!

I'm trying to create a combobox in the admin to let the user select one value and I have not idea how to create this in the model:
public $validate = array(
'language' => array(
'inList' => array(
'rule' => array('inList', array('es','cat','Home','null')),
'allowEmpty' => true,
)
)
);
this works but not shows the options in Combobox to the user, only validate the result,
Do someone know how to do it????

Thanks in advance,