Css background problem

Hi yesterday I started creating a website usingonly HTML CSS and Photoshop.I decided to use as backgroound an image that I found over the internet but I dont realy know what size should I make the Image so that it will look the same on any resoluztion.

Any suggestions?

This is the image I am using

http://www.google.ro/imgres?q=underwater&hl=ro&biw=1366&bih=667&gbv=2&tbm=isch&tbnid=dnNKiqNL0-pNWM:&imgrefurl=http://www.wallpaperweb.org/wallpaper/nature/underwater_8323.htm&docid=KWgRgTNbop2oLM&w=1280&h=1024&ei=H5NnTqTTD-jQ4QTkhYHVDA&zoom=1&iact=hc&vpx=642&vpy=286&dur=1390&hovh=201&hovw=251&tx=111&ty=108&page=15&tbnh=155&tbnw=194&start=220&ndsp=15&ved=1t:开发者_Go百科429,r:12,s:220

It's impossible to make the image look exactly the same at every resolution. However, if you simply want to scale it to fill the page, though, you could take a look at this SO question and answer.

Thats a bit tough to tell but you might get away with using a jQuery plugin such as backstretch

That image can't be set to be shown the same in all resolutions. You'll need to find one which has a gradient which changes to one color. Then you can set your background color to be the same as the ending color of the image.

Hope this helps.