To pass your parameters, you add a location template string and then set values for its parameters. See this description in the docs»
”In the Call REST dialog box, click Edit for the Location and add the following to Template: https://en.wikipedia.org/api/rest_v1/page/summary/{1}
, with the parameter being the Title attribute from the Input parameter $Input/Title
. Click OK.”
For complete details on consuming REST service in Mendix, please go through the documentation which also has an example. https://docs.mendix.com/howto/integration/consume-a-rest-service
Also see the configuration of Call REST activity used in microflow here: https://docs.mendix.com/refguide/call-rest-action