I’m not sure, as I don’t really use translations.. this sounds like a general WP question that you may want to post in the main WP forum (maybe under “Plugins” forum). Just ask how to enable your language in the plugins that you are using. Also there is lots of info on the topic of localization and translation available online, just try using a search engine for more information. For example, here is an article that looks useful:
https://codex.ww.wp.xz.cn/Installing_WordPress_in_Your_Language
well.. it’s YOUR plugin… so who else should know how to activate the plugin language? 🙂
my wp theme is already set to danish… but the user submit post is made in english…
I have made the danish po file, and transferred it via my ftp program… but I have to tell the plugin which language to use, right?
Correct, it is my plugin, and I have implemented full translation support, as you can see by the many translations that are available in the languages directory. I do not use translations myself, however, so I do not know how to tell WP to use a particular language. That is something that I assume is left to the end-user, who may be needing the translation. Again, I would ask in the general forum and also do some research online, for further information. I hope this helps.