How Do You Make People Nude On Gimp?

Theres no program that will remove clothes. If you must make your own nude (There are thousands on line that are free and legal though) You can copy and paste using the select and cropping tools in GIMP to make your own nudie, but the time you will have to spend learning to use the tools will quickly frustrate anyone who just wants to make pics for "self gratification." GIMP is a powerful and very capable tool for doing such but I suggest you just google "naked girls" and leave the GIMPing to those of us who know how to use GIMP and what to use it for....just don't let your mom catch you.

You could always use the smudge tool. Just start with a patch of bare skin somewhere on the subject and use smudge throughout the entire body, once you have a blank slate you can then use free select with feathered edges and lower the brightness to create shadows, giving the illusion of certain body parts

No but you can see through the clothes. There is a program called fake-flesh that makes people naked but its quite expensive