Welcome to the forum.
Starting from scratch, there are different ways such a thing can be done. I'll assume you've already added the series and it's episodes to your database using an import plugin (e.g., IMDb, TVDb). If your DVD has been ripped so each episode is in a separate file, the next step is to associate those files with they're respective episode records. Just so you know, that can be done manually—by entering the [File Path] for each. But the easier way is to use Tools > Scan folders... to do the same thing automatically. For that to work, your files have to be named according to some consistent pattern that includes the series name, season and episode number (e.g., Series title S01 E01.mkv). Then your configuration (at Preferences > File Scanner) must include a Regular Expression that matches that pattern (e.g., (?i)^.*\\(?P<title>.*)(s|\b)(?P<season>[0-9]{1,2}) ?e(?P<episode>[0-9]{2,3})). I don't expect you to understand the latter, but have a look and try to determine if that's the problem. Also, let us know what file name pattern you're using.
