Vim is a text editor. Based on the vi editor common to Unix-like systems, Vim is designed for use both from a command line interface and as a standalone application in a graphical user interface. Vim is free and open source software. It is cross platform ans can be used on different computer operating systems.
This Praxis Program has text and video tutorials to help you learn to use the text editor Vim: http://praxis.scholarslab.org/tutorials/vim/