Help with code for Api key to read from file and repeat on scheduled times

Hi there, I'm looking for help here with an API for a website called Gameflip, gamaeflip is a website where you can sell digital in-game items, for many games, I've been a seller there for many time, they offer an API key for sellers to make items posts using their API or manually, I've been doing manually for a long time but I'd like to make it automatically with using this API, I've tried myself to do it but couldn't make it to repeat the items posted. Normally you can post in their site manually by adding description, quanitity, price and a picture of your item but this takes a lot of time compared to the API (1min vs 5secs per post), so what I'm looking for is to post faster using their API so I can just make a list with the things I want to add to each post. Website: [login to view URL] Information about gameflip API: [login to view URL] Rocket League Sample Code: [login to view URL] Here is the info about things you can do using their API, I'm aiming for posting rocket league items and CSGO items if possible. I don't know about coding but I'm open to learn if needed. Any doubts please share them to me.