Backround Wallpaper Size

How can i put a backround wallpaper with domensions 1920x1080 without make any error to the template. I use style 1 of Hot Sportal. Thank you !

You can just replace this pattern image with your image:

/sportal/templates/hot_sportal/images/bg_1.png

but you say you image is 1920x1080 , I assume some designed graphic. If you want it to cover all page add:

body {
background-size:cover;
}

at bottom of template_css.css

(this will not work in old browsers)

Sorry for intervention, but is it possible to avoid background reapeating when scrolling down the site?
I.e. i'd like a fixed background image that doesn't scroll when i scroll all the text/site.
I've attempted to modify .css without results...

Yes:

body {
background-size:cover;
background-repeat:no-repeat!important;
}