First of all, you must contact the EVOLVED-5G organization to be able to test your Network App in the EVOLVED-5G facilities, the Athens & Malaga 5G Platforms.
You also need to ensure that your Network App is following the specifications required for its validation running EVOLVED-5G tests (e.g., containeirization, use of a external configuration file following the same format as specified for this aim in EVOLVED-5G). And that your Network App has already successfully passed the verification phase, passing all perfomance tests with the NEF emulator and the CAPIF tool. That is, that your Network App is working as expected and the interface interaction with the 5GC and the NetApp API exposure is performing as intended.
For both actions, validation and certification, you need to access to the EVOLVED-5G framework, store your Network App in the Open Repository and make use of the CI/CD pipelines.
For validation, you will need to contact with the validators from the 5G platform, to coordinate with them and validate your Network App along with an associated vertical App that makes use of it by consuming the Network App APIs.
For certification, the testing process will be automatic.