CMS - How to add new field to article editor?

[rellect]

Hello ,

I want to build a plugin that add a new field to article editor and it would be possible to enter a link of image,
This picture actually replace the original preview image of the article.
My problem is how to save the information of the field (input) ..
Which HOOK I need use?
Which functions I need to use?

[ragtek]

You could use hook vbcms_article_save_start

[rellect]

You could use hook vbcms_article_save_start
How?
What I need write? New Query?

I think I should somehow combine the existing query, but I don't know how..
You can help me?