How do zsh ansi colour codes work?

Running the following code in your terminal should tell you whether your terminal supports 256 colors.

for COLOR in {0..255} 
do
    for STYLE in "38;5"
    do 
        TAG="\033[${STYLE};${COLOR}m"
        STR="${STYLE};${COLOR}"
        echo -ne "${TAG}${STR}${NONE}  "
    done
    echo
done

it also shows you the code for each color in the form 38;5;x where x is the code for one of the 256 available colors. Also, note that changing the "38;5" to "48;5" will show you the background color equivalent. You can then use any colors you like to make up the prompt as previously mentioned.

First off, I'm not sure what terminal you're using or if it will even support the color orange. Mine supports the following: Red, Blue, Green, Cyan, Yellow, Magenta, Black & White. And here's how I get colors in my terminal:

---

You need to first load the colors using autoload. I use the following to load the colors and assign them to meaningful names

#load colors
autoload colors && colors
for COLOR in RED GREEN YELLOW BLUE MAGENTA CYAN BLACK WHITE; do
    eval $COLOR='%{$fg_no_bold[${(L)COLOR}]%}'  #wrap colours between %{ %} to avoid weird gaps in autocomplete
    eval BOLD_$COLOR='%{$fg_bold[${(L)COLOR}]%}'
done
eval RESET='%{$reset_color%}'

You can set the hostname in your prompt using the %m string. So to set, say a red hostname, you'd do

${RED}%m${WHITE}\>

which will print something like bneil.so>