Hi @hakan_cetinkaya,
Thank you for your willingness to help us resolve this!
If you go to KoBoToolbox localization and click Help translate KoBoToolbox
button, you will be able to sign up there and it will send us a request to add you to the project. I will add you to the Turkish language so you can review it.
The documentation for Transifex is available here. Here . Please let us know if you have any issues.