Troubleshooting HTTP API: Clay 101 ImageFlip Template Issues

I was learning HTTP API from the yash example in Clay 101 course (https://www.clay.com/university/lesson/http-api-clay-101) I am close to getting it done but it doesnt add text to imageflip templates i got it gives out message "No text specified, Remember, API request params are form url-encoded http parameters, not JSON" I also tried adding Header (optional) Content Type. " application/x-www-form-urlencoded" Image flip requires url encoded and clay is giving JSON i think Please assisst. Clay S.