Tell us what you are trying to do?
I want users to be able to select options from a dropdown menu (or color swatch selector) on the woocommerce single product page, using a custom field. For example, a dropdown menu labeled "color" from which they can choose red, blue, or green.
Is there any documentation that you are following?
I guess you would like your dropdown menu to do something, i.e. this is not a dropdown menu to be used on a form where users submit products, rather you want to add a field with options to the product page which become part of the order details when a product is added to the cart and goes through checkout.
Toolset can help with the former, but not so easily with the latter, and the "do something" part would need to be done via custom code.
There are plugins available for this if you don't want to code, this article appears to offer a good overview: hidden link