1. Create localization project
Login to your account, create a new localization project and add a language to it.
2. Import localization file
In the project page, use the Import Terms functionality in the Options Menu on the right to import your xmb file, with translations in the language you created.
This language will automatically be set as your project's Default Reference Language after you import the translations. You can change the DRL in Project Settings.
3. Start localization
Add your desired languages for translation, invite your contributors to join and start localizing your app.
When the app localization is completed, you can export your localized .xtb file, using Export button in the language page.