.link1 a{ 
    background-image: url(images/link_start_on.png);
    background-repeat:no-repeat;
}
.link2 a{ 
    background-image: url(images/link.png);
    background-repeat:no-repeat;
}
.link3 a{  
    background-image: url(images/link.png);
    background-repeat:no-repeat;
}
.link4 a{ 
    background-image: url(images/link.png);
    background-repeat:no-repeat;
}
.link5 a{ 
    background-image: url(images/link.png);  
    background-repeat:no-repeat; 
}
.link6 a{ 
    background-image: url(images/link_end.png);  
    background-repeat:no-repeat;
}