1. Log in to your Apple Developer account and go to the App Store Connect dashboard.
2. Click on the app that you want to invite testers for.
3. Click on the "TestFlight" tab in the top menu.
4. Click on the "Internal Testing" or "External Testing" section, depending on whether you want to invite your own team members or external testers.
5. Click on the "+" button to add a new tester.
6. Enter the tester's email address and select their testing role (either "Tester" or "Developer").
7. If you want to add multiple testers, click on the "+" button again and repeat the process.
8. Once you've added all the testers you want to invite, click on the "Save" button.
9. TestFlight will send an email invitation to each tester you added. They will need to follow the instructions in the email to download the TestFlight app and access your app's build.
10. After the testers have downloaded the TestFlight app, they will be able to install and test your app's build.