button to increase stock amount WC

Hi,
I’m trying to experiment with woocommerce through a custom plugin.
what am I trying to do?
Insert a button on Woocommerce shop page to increase product quantity.

Code button is this:

add_action( 'woocommerce_after_shop_loop_item', 'mycode_plus_buttons', 1 );
function mycode_plus_buttons() {
    add_action( 'woocommerce_after_shop_loop_item', 'mycode_plus_button' );
}
function mycode_plus_button() {
	global $product;
	echo '<a href="' . get_permalink( $product->id ) . '" class="button add_to_cart_button product_type_external">+</a>';
}

Now, I found the command wc_update_product_stock () at this page:
here

but I don’t know how connect code of API to button on shop page.
can someone tell me some examples to study to solve my problem?
Thanks
Luca