How to add tooltip in thumbnail image

Hi all
How do I add a tooltip for the image thumbnail
My Site http://www.retete-super.ro
I found examples but I do not know how to do it
http://www.menucool….tip/css-tooltip
http://wpfaq.org/site/tooltips-2/
I want to appear on each picture
Every thin coloring with red border
View picture text will appear
How do I make this change without plugin
Thank you!

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