I know how to use a module to create a block and I know how to create a custom form using form api.
now, i want to add this custom form inside the block I create.
Use the following code (hook_block_view):
function yourmodule_block_view($delta='') {
$block = array();
switch($delta) {
case 'block_name':
$block['subject'] = t("Block Title");
$block['content'] = drupal_get_form('your_form_id');
break;
}
return $block;
}