Write codes for foreign keys of this db (MySQL)?

My db structure is as below and I also have some data. How do I specify foreign keys using the MyIASM engine?

I have read the MySQL webisite, but because I am afraid of making errors I am asking you to show me an example.

• one article can belong to many categories.
• one article can have zero or many photos.
• one article ca开发者_StackOverflow中文版n have zero or many tags.

My db structure:

tb_categories|cat_id(pk) , catname , parent_id
tb_articles|article_id(pk) , title , subtitle , textbody ,  date , remark
tb_articles_categories|id(PK) article_id(fk) , cat_id(fk)
tb_phptos|photo_id(pk) , photofilename , article_id(fk)
tb_articles_photo|article_id(fk) , photo_id(fk)
tb_tags|tag_id(pk) , tagname
tb_articles_tags|id(PK) article_id(fk) , tag_id(fk)

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MyISAM does not support foreign key constraints, so you don't.

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MyISAM does not support foreign keys. Only InnoDB does.