D-data, backup is Full - all red

Hello, I have jsut acaqired a new new Toshiba laptop. My D-data backup is full, almost all red; 116Gb and 105Gb used. But when I look at the size of the files in the D-drive, only < 6Gb are used. I am a single home user, no network. So the question is how to I restore it and keep only the backup files, and/or necessary stuff.
Thanks