How to set default vim colorscheme

Put a colorscheme directive in your .vimrc file, for example:

colorscheme morning

See here: http://vim.wikia.com/wiki/Change_the_color_scheme

Your .vimrc file goes in your $HOME directory. In *nix, cd ~; vim .vimrc. The commands in the .vimrc are the same as you type in ex-mode in vim, only without the leading colon, so colo evening would suffice. Comments in the .vimrc are indicated with a leading double-quote.

To see an example vimrc, open $VIMRUNTIME/vimrc_example.vim from within vim

:e $VIMRUNTIME/vimrc_example.vim

It's as simple as adding a line to your ~/.vimrc:

colorscheme color_scheme_name