This is my pretty basic ~/.virmc. Lines starting with a double quotation mark are comments:
" Make text pop out on dark backgrounds:
set bg=dark
" Always display line numbers:
set number
" TAB width is 4:
set tabstop=4
" ...and so is an INDENT:
set shiftwidth=4
" Make TAB insert an INDENT at the beginning of a line:
set smarttab
" TAB is 4 SPACES instead of one \t:
set expandtab
set modeline
Image credit: Wild Grazing - Sheep grazing on the southwest coast of Ireland. In the Public Domain. Source.