Your "my-post" page will be almost the same as the "index" page. The difference is that you fix the owner of the post in the search model to the current user.
public function actionMyPost()
{
$searchModel = new PostSearch;
$searchModel->createdBy = Yii::$app->user->identity->id;
$dataProvider = $searchModel->search(Yii::$app->request->queryParams);
return $this->render('my-post', [
'searchModel' => $searchModel,
'dataProvider' => $dataProvider,
]);
}
The "search" method of the search model will filter the result by the owner of the post.