Hi,
The Print On Demand example can be a good start to learn how to create a product page with configuration option. Another useful example is the Product Configurator example .
As for the price change, after selecting the relevant color (or size) from the dropdown and clicking on the Add To Cart button, you should add to the cart the product with the relevant product option.
Here’s a snippet which should better explain what I’m referring:
export function addToCartButton_click(event, $w) {
let colorSelected = $w('#dropdownColor').value;
//in case it's a dynamic product page
let itemObj = $w("#dynamicDataset").getCurrentItem();
$w("#shoppingCartIcon1").addToCart(itemObj._id, 1, { choices: { Color: colorSelected} });
});
I recommend also reading the documentation here. There are other examples there with explanation how to use the function.
Good luck,
Tal.