How to properly link mysql tables?

Question

MySQL

The PHPMyAdmin database has two tables, articles and comments, which share a page _id column. I want to link them through this column with this query:
ALTER TABLE `comments` ADD FOREIGN KEY (`page_id`) REFERENCES `articles`(`id`) ON DELETE RESTRICT ON UPDATE RESTRICT;
MySQL Answer: Documentation #1452.
What am I doing wrong and how to connect them correctly?

Answer 1

Make sure that for each page_id value in comments there is a corresponding id in articles.

Answer 2

I think the answer is contained in the documentation #1452