How do I set the prompt to use two colors?

Run the following command in a terminal:

gedit ~/.bashrc

When .bashrc opens, locate and uncomment force_color_prompt=yes (that is, remove the hash, so it no longer looks like: #force_color_prompt=yes).

Save the file, and open a new terminal window, and you should already see a change (the prompt should be Light Green, which is defined by 1;32). You can then change any colour value you like; eg: 0;35 = Purple.

To edit the colour values, locate the following section, and change the default values with some of the examples listed further down:

if [ "$color_prompt" = yes ]; then
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;31m\]\w\[\033[00m\]\$ '
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

You can check out this Bash colour chart for a full range of colour values, but here are a few basic ones you can play around with (note that “Light” isn’t what you might think – it actually means “bold”): Black 0;30 – Dark Gray 1;30 – Blue 0;34 – Light Blue 1;34 – Green 0;32 – Light Green 1;32 – Cyan 0;36 – Light Cyan 1;36 – Red 0;31 – Light Red 1;31 – Purple 0;35 – Light Purple 1;35 – Brown 0;33 – Yellow 1;33 – Light Gray 0;37 – White 1;37

For example, here is the line that I use it:

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;35m\]\u@\h\[\033[00m\]:\[\033[01;34m\] \w\[\033[01;37m\] > '

or, my girlfriend, use:

PS1='${debian_chroot:+($debian_chroot)}\[\033[01;36m\]\u\[\033[01;31m\]@\[\033[01;36m\]\h\[\033[01;33m\]:\[\033[01;31m\]\w\[\033[01;33m\]\# '

Feel free experimenting by setting your prompt by changing the value of the PS1 environment variable in Terminal, as follows:

export PS1="...your values..."

or, just

PS1="...your values..."

Here is how my terminal look:

Source: http://ubuntugenius.wordpress.com/2011/07/11/how-to-change-the-command-line-prompt-colour-in-the-ubuntulinux-terminal/

Simply modify $PS1 in the shell startup files with the appropriate calls to tput in order to set and clear text attributes. See the tput(1) and terminfo(5) man pages for details.

export PS1="\[$(tput setaf 2)\][\u@\h \W]\$ \[$(tput sgr0)\]"

This thing you are talking about is called prompt. There are lots of options and scripts to modify your prompt using different colors and displaying any kind of additional information. A good start with some examples can be found within jamie's collection and IBM has some nice explanations for beginners. If you want to go more into detail have a look at this comprehensive howto