Beginner to API Json - Attempting to understand URL output

I am using FME to get output from the following: https://coronavirus.data.gov.uk/developers-guide

I am just a beginner and is first time I want to write this up. To generate an Output URL from this with the relevant columns, can anyone explain what I need to get the request URL. I am using GET as the HTTP method

An example of a url i get some data out of is - https://soa.smext.faa.gov/asws/api/airport/status/SFO

But when i try with the links below which i tested does not get any output https://api.coronavirus.data.gov.uk/v1/data?filters=areaType=nation;areaName=england&structure=%7B%22name%22:%22areaName%22%7D

https://api.coronavirus.data.gov.uk//v1/data?filters=areaType=nation;areaName=england&structure={"date":"date","areaName":"areaName","areaCode":"areaCode","newCasesByPublishDate":"2020-07-07","cumCasesByPublishDate":"2020-08-08","newDeathsByDeathDate":"2020-02-06","cumDeathsByDeathDate":"2020-06-09"}

This is a better link for you to try out.

https://api.coronavirus.data.gov.uk/v1/data?filters=areaType=nation;areaName=england&structure={%22date%22:%22date%22,%22areaName%22:%22areaName%22,%22areaCode%22:%22areaCode%22,%22newCasesByPublishDate%22:%22newCasesByPublishDate%22,%22cumCasesByPublishDate%22:%22cumCasesByPublishDate%22,%22newDeaths28DaysByDeathDate%22:%22newDeaths28DaysByDeathDate%22}

Took me a while to suss it out.