How to set tab to 4 spaces in vim?

Create a ~/.vimrc file with this line:

set ts=4 sw=4

This will set tabstops every 4 spaces and set the shiftwidth (that amount you indent) as 4 spaces also to match your tabstops.

Make ~/.vimrc and add this:

set tabstop=4

Here are some other helpful ones:

syntax on " Syntax highlighting
set showmatch " Shows matching brackets
set ruler " Always shows location in file (line#)
set smarttab " Autotabs for certain code
set shiftwidth=4