Add down drop lists in body of page

Hi,
I’ll like to create a drop down list not in the menu header bar, but in the body of the page.
How do I do that?

I’ll like to create a drop down list such that the item chosen from the list will change the link of a button that I’ve created.
Think of it as creating a e-commerce shop page. If I chose item 1 from the drop down list, the “add to cart button” will be linked to that for item 1.

Thank you.