Hi Jaya,
first I would advice you to take this learning path about integrations: https://academy.mendix.com/link/modules/138/lectures/1226/5.1-Consume-a-REST-Service
When you need to show the results of to API's in one graph
- incase it is same kind of data; create import mapping for both API's using the same data entities and use these in the graph
- When it is different data and you want to compare/show them together in a graph. Create a mapping per API. and use the root object of both API's as source of the graph