Telling Weblate what languages you understand/translate will make it easier afterwards. You can also take a moment to edit your account profile and settings if needed.
Weblate will now present you with text in need of translation or correction. Confidently submit a translation, or fill-in your proposal and submit the form. If you're not sure at all, comment or move to the next string.
Get used to the interface by try to view in detail your current location, or another location of your choice. You may also search a location by name in the search bar.