Shiva,
Documentation for this can be found at docs.mendix.com. A good place to start might be here: https://docs.mendix.com/howto/integration/consume-a-rest-service
Also, there is an expert webinar you can watch on Youtube. The webinar is for version 6.6 but will be applicable in version 7.1, I think. Webinar can be found here: https://youtu.be/eeWAqnny5xE
Hope that helps,
Mike