As per your question you have managed everything except assigning points to user.
Then I suggest you to have a rule with execute custom php code.
The code for assigning points to user is as follow. (Do your necessary changes accordingly.)

$params = array(
    'uid' => $user->uid,
    'moderate' => 0,
    'points' => 15,
    'tid' => 0,
    'entity_id' => $user->uid,
    'entity_type' => 'user',
    'operation' => 'Vote Added',
);

userpoints_userpointsapi($params);