How to create .install custom file How to create and add .install file for druapl8 custom form data storage...my file is custom_form.install but my custom module not load this file

&lt;?php
/**
* Implemetation of hook_schema()
*/
function custom_form_schema() {
$schema=array();
  $schema['custom_form'] = array(
       'description' =&gt; 'An example form table',
    'fields' =&gt; array(
      'fe_id' =&gt; array(
        'description' =&gt; 'The primary identifier for a form.',
        'type' =&gt; 'serial',
        'unsigned' =&gt; TRUE,
        'not null' =&gt; TRUE,
      ),

      'firstName' =&gt; array(
        'description' =&gt; 'A field storing text',
        'type' =&gt; 'text',
        'length' =&gt; 50,
        'not null' =&gt; TRUE,

      ),
'lastName' =&gt; array(
        'description' =&gt; 'A field storing text',
        'type' =&gt; 'text',
        'length' =&gt; 50,
        'not null' =&gt; TRUE,

             ),

'emailId' =&gt; array(

        'type' =&gt; 'varchar',
        'length' =&gt; 50,
        'not null' =&gt; TRUE,

             ),

'pass' =&gt; array(
                'type' =&gt; 'varchar',
        'length' =&gt; 50,
        'not null' =&gt; TRUE,

      ),

'likes' =&gt; array(
       'description' =&gt; 'A field storing Likes',
        'type' =&gt; 'text',
        'length' =&gt; 200,
        'not null' =&gt; TRUE,

      ),

'gender' =&gt; array(
        'description' =&gt; 'A field storing Gender',
        'type' =&gt; 'text',
        'length' =&gt; 50,
        'not null' =&gt; TRUE,

      ),

'description' =&gt; array(
        'description' =&gt; 'A field storing Description',
        'type' =&gt; 'text',
        'length' =&gt; 255,
        'not null' =&gt; TRUE,

      ),

),

     'primary key' =&gt; array('fe_id'),
  );
  return $schema;
}
?&gt;
You need to create the schema using the following code

$schema = Database::getConnection()-&gt;schema();
$schema-&gt;createTable('custom_form', $spec);


For further details visit here