Picture auto resize in description to viewable

[TheTester]

Hello!!

I included some images on the product description ( Catalog - SubCatalog - Product - 1. Info ->> Description)
(like: )

its work, but the problem is: the image too big, and cutted the right side.

How, and where i need to change the original presta sourece, to include some: str replace or preg replace to AUTOMATIC change the picture size to smaller and when i Click to the picture the picture comes bigger, like the thumb on the top.

Thank you!