Sorry, i pasted this code from another forum and it works now. Thank you
body .woocommerce .add_to_cart_button {
margin: auto;
float: none;
display: block;
text-align: center;
}
.quantity {
text-align: center;
}
.woocommerce ul.products li{
text-align: center
}.product, .woocommerce-page ul.products li.product{text-align:center;}