Open Jmeter and add Thread Group
Under Thread Group add HTTP Request, View Results Tree, Response Assertion
In HTTP Request set Server Name: samples.openweathermap.org (for example) and set Path as /data/2.5/forecast and then Add Parameters. Under Name write id and its value 524901 and appid and it's value b1b15e88fa797225412429c1c50c122a1
In the View Results Tree, all results must be correct.
In Response Assertion under Custom Failure Message write 200

Screenshots Of REST API Testing: -

REST API Testing With Jmeter