Problem Regarding Ecommerce APIs

Hi Guys,

I am stuck in some problems regarding the uses of APIs.
my task is to upload single/Bulk product over Ebay and Amazon using their APIs, I got lots of APIs as well but I didn't the accurate way to implement that thing if anyone have any GUI kind of sample or having any idea how to accomplish desire task, then let me know.
and if anything that you don't understand properly than also let me know.
Thanks in advance