File folders

I am loading mp3 music files from my pc onto the ‘album’ folder of a clip+ using drag & drop.  No problem with commercial CDs, all tracks appear under the original album title.  All other tracks, such as those converted from audio cassettes, are in named folders on the pc but appear lumped together under “unknown” album on the Sansa.  Is there any way to retain these in groups under the proper album titles when transferred?

Many thanks.  I modified the ID3 tags info. through Windows explorer on the pc, without any other software, and everything now works well.

Cheers!

Update.  Now downloaded and used the free software, MP3tag, as recommended by Miikerman.  Much quicker and easier than using Windows explorer. Gets better all the time!