How do you get started doing the "pick from list" program.

[disneyshopper]

What you are asking about is called Variations.  Not all categories support that feature.  Here are some topics fpor you to review:

https://www.ebay.com/help/selling/listings/creating-managing-listings/creating-listings-variations?
id=4150

https://export.ebay.com/en/listings/how-optimize-your-listings/how-to-create-listings-with-variation...

https://pages.ebay.com/sellerinformation/sellingresources/multiplevariationslist.html

http://shipscript.com/ebayhelp/lister_hub/creating_ebay_variations.htm