How to create custom cck field in drupal 7

Plz tell me hw to show the file attachment field with the schema. and also give the module file in which we defined the these element in our front end.

This is a support request

/**
* Implements hook_install().
*/
function collabfield_install() {

}

/**
* Implements hook_uninstall().
*/
function collabfield_uninstall() {

}

/**
* Implementation of hook_field_schema().
*/
function collabfield_field_schema($field) {

if ($field['type'] == 'collabfield') {

$schema['columns']['name'] = array(
'type' => 'varchar',
'length' => '255',
'not null' => FALSE,
);

$schema['columns']['position'] = array(
'type' => 'varchar',
'length' => '255',
'not null' => FALSE,
);

$schema['columns']['telephone'] = array(
'type' => 'varchar',
'length' => '255',
'not null' => FALSE,
);

$schema['indexes'] = array(
'name' => array('name'),
'position' => array('position'),
'telephone' => array('telephone'),
'fid' => array('fid'),
//'mail' => array('mail'),
);

return $schema;
}
}

I havecreated the text field but ididnot able to crate the file attachment hw we create the schema for file attachment.