var i;

function SetBg(myi){
    i = myi;            
    document.getElementById('Container').style.background = "url(i/bg/" + i + ".jpg)";
}
function BgBack(){
    if(i==0){
        i = 8;
        SetBg(i);
    }else{
        SetBg(i-1);
    }
}
function BgForward(){
    if(i==8){
        i = 0;
        SetBg(i);
    }else{
        SetBg(i+1);
    }
}