td{
    width:200px;
    height:200px;
    border:2px solid blue;
}
.caixa1{
    background-image: url('img/um\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}
.caixa2{
    background-image: url('img/dois\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}
.caixa3{
    background-image: url('img/tres\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}
.caixa4{
    background-image: url('img/quatro\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}
.caixa5{
    background-image: url('img/cinco\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}
.caixa6{
    background-image: url('img/seis\ \(1\).jpg');
    background-size:200px;
    background-repeat: no-repeat;
}