I want to import a project that I'm planning to build upon. The problem is that it is very messy; with source files, class files and libraries under one directory. How would I organise these files using Eclipse?

I know you can change the source folder and output folder, but when I do change the source folder, the files that I want inside it do not physically move to that folder. Output folder is fine, though. Also, I would like a separate folder for libraries. I'm not sure how I would go about this, however.

Here's how I would like it:

src: This folder will contain source files.
bin: This folder will contain binary (class) files.
lib: This folder will contain external libraries.