Creating Service catalog request by using a json file.

Hi , I am trying to create a service catalog request in ServiceNow using a json file. I can create a request in service catalog by using the json file created by the ServiceNow by using the network tab in chrome. But i got a json file which is created in diffrent API, that json file contain different attributes with different and new field. So if i have to create a service Catalog by using json file how can i do it ? Do I have to create a variable set for the service catalog request  form?