zsh

sh -c "$(curl -fsSL https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

Enable Any Oh My Zsh Plugins

Oh My Zsh comes with a ton of plugins you can take advantage of. Here is the wiki page.

Open your ~/.zshrc file via Terminal

open ~/.zshrc

Find and edit the plugins section to add the ones you want

# Example format: plugins=(rails git textmate ruby lighthouse)
# Add wisely, as too many plugins slow down shell startup.
plugins=(git brew ruby osx)

Open your ~/.zshrc file via Terminal

open ~/.zshrc

Modify the theme. You can find a list of the themes here

Make sure to save and close the file after editing. You may have to quit and reopen iTerm2 for the theme to take effect.