i just made a new layout image for my site and i was trying to code it. and the only thing i have is textedit.
so as i was coding i tried to save it to a .php file but it wouldnt save... so i cant view it anywhere :[
what can i use?

i hope im making sense?

PHP.

http://php.net/index.php

textwrangler.
its free and amazing.
also, if you want to pay for something (?) bbedit and textmate are the other two best options. but I textwrangler is just as good. I love it.

And the highlighting is very useful.

called syntax highlighting, standard in almost every text editor.

I'd like to throw in a second recommendation for Textmate. It's not free, but it's a beautiful piece of software that I use not only to work with PHP, but also CSS, HTML and RoR.