Is this an X terminal you are wanting to change the color in, or are you wanting to change the colors of all terminal sessions, even without Xorg? Let us know what terminal app if you are talking about an X terminal (xterm, aterm, Eterm, konsole....), or if you want to change the color of all terminal sessions, please name the shell you are using, or if you don't know; mention the distribution, or post what it says next to "SHELL" if when you type 'env'.
Since you mentioned wanting to know how to do so from the terminal, I will post an example coming from the most used shell in Linux (bash), and how to change the color of prompt, and the overall terminal.
That will change your prompt to a Christmas style prompt.
host:~ KernelKiller$ echo $PS1
\h:\W \u\$ (your current prompt layout)
// h = host, W = working directory, u = user, $ = the "$" you see at the end
host:~ KernelKiller$ export PS1="\e[0;31m\h:\e[m\e[0;32m\W \u\$ \e[m "
For the color of the entire terminal use 'setterm': setterm -[background|foreground] [color]
$ setterm -foreground green