HA translation - How to add new strings to lokalise?

Hello,
which tools are required to prepare translate HA, with adding new string to lokalise (not yet prepared the sentences for translation)?
How to process new string, please?

Whenever a new string is added in a PR to the main github codebase, those strings get synced to localize regularly. So you don’t add anything to localize itself, you just add your new string keys in the codebase.

What I need to install, please?