Manual add

Is it possible to manually download and add a subtitle when using Kodi?

The subtitle add-on is not working for me. It managed to get it to work exactly once. I downloaded and installed subtitle for one movie. Now I just gives an error and tells me to check the log file. Which I wont do, refuse to do, as a matter of principle.

The better way to do this is to manually download and install and not let add-ons do that. Hoping that Kodi will be able to use subtitles. It is a basic function so I am hoping Kodi can perform it.

I have download a subtitle. How can I add it to a movie? How can I do that?
Thanks,
Onno