Drop Down To Get Data From All Clothes Sizes

I am trying to scrape a site that sells clothes. When I get to the detail page, I want to choose a size, scrape the data, choose the next size, scrape the data, etc. I read the post in this forum on the subject ("Please Help: How To Setup Drop Down Selection"), but I don't know what to select on the page to get the Click Selector to work. I cannot figure out any combination of selections that will get: div > div[class^='form-group'] > select > option:nth-child(n+2)
A video tutorial would be very helpful but can someone describe the element(s) you need to select and whether it is S, P, or C?
So, yes, when I test the Marine Depot example site map, it works fine but I can't translate it to what I need to do.

See the following:



Thanks. After reading some more examples (and realizing that I really needed to dig into the CSS selector tags manually), I got something to work.