oh-my-zsh provides us beautiful themes. Here are the steps that I took to install oh-my-zsh on my macOS 10.12.

1. Install HomeBrew

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

2.Install zsh (It is default installed on macOS)

brew install zsh zsh-completions
chsh -s /bin/zsh

3. Download the oh-my-zsh package and install

git clone git://github.com/robbyrussell/oh-my-zsh.git ~/.oh-my-zsh 
cp ~/.oh-my-zsh/templates/zshrc.zsh-template ~/.zshrc

4. Change the themes, etc..