Hi yashar-2009, welcome to Thunkable! 
Be sure to check out How to ask Great Questions v2.0, the Community Guidelines, and our Getting Started Guide to make the best of your Thunkable Community experience!
As for your current setup, the “URL from uploaded file” block should upload the selected file to Cloudinary already. Unless you have a particular reason for using the API, I would recommend following the steps here to connect your Thunkable app to Cloudinary to easily upload images.