There's a popular stackoverflow answer as a Vim (Vi) introduction, which I haven't read through but will link anyway: https://stackoverflow.com/questions/1218390/what-is-your-mos...
http://vimcasts.org/episodes/ screencasts are high quality short videos, go back to the early ones for introductions to buffers and windows and things (more recent ones tend to be too many niche scripts and plugins for me).