want a drop down menu to choose services

hi
I wanted a wordpress plugin that allow me to choose from a drop down menu if services and click the buy button. So I think this plugin can do it. but dont know how. can you help me with this.
I want like this..

{dropdown1
dropdown2
dropdown3}…… choose one then click on buy .

this will be services

thanks

https://www.ads-software.com/plugins/simple-e-commerce-shopping-cart/