Look in your users home folder. Do you have a hidden file called .vimrc? If so, edit (or create it if it doesn't exist) and add these lines:
# show line numbers
The colorschemes are located in /usr/share/vim/vim63/colors. Try them all to find one you like, then edit the :colorscheme line in .vimrc to use that colorscheme.
To find other options you can set in .vimrc, in a terminal window start vim. Then in command mode, :help set (or any other topic) to find out what you can set.