To use FHIR API with your healthcare application, you will need to follow certain steps:  

1. Understand FHIR: FHIR (Fast Healthcare Interoperability Resources) is a standard for exchanging healthcare information electronically. Before you start using FHIR, it is important to understand its structure, components, and how it works.

2. Choose a FHIR server: You can choose a FHIR server that is compatible with your application and provides access to healthcare data. There are several open-source and commercial FHIR servers available that you can use.

3. Authenticate and authorize: Once you have selected a FHIR server, you will need to authenticate and authorize access to the data. This may require obtaining an access token or API key from the FHIR server.

4. Use FHIR APIs: FHIR APIs provide a set of endpoints that allow you to interact with the FHIR server and retrieve or send healthcare data. You can use FHIR APIs to create, read, update, or delete healthcare data.

5. Implement FHIR resources: FHIR resources are data models that represent healthcare concepts such as patients, medications, or observations. You will need to implement these resources in your application to interact with the FHIR server and exchange data.

6. Test and validate: Once you have implemented FHIR APIs and resources, you should test and validate your application to ensure that it works as expected and complies with FHIR standards.

It is important to note that simply importing the FHIR API file is not sufficient to use FHIR with your application. You will need to follow the above steps to properly integrate FHIR into your healthcare application.