Hi Kim.
Any text editor can edit php files but as php is a server side scripting language I'm afraid you cannot view the output.
There are two options available.
1. Upload your edited files to a webserver and view them in your browser.
2. Setup a webserver on you own computer.
Option 2 is not as hard as it may sound, there are a few packages that will setup the apache webserver with php perl and mysql already configured and ready to go.
If you want to try that then go to
http://www.firepages.com.au/ and select the phpdev4 package.
Hope that helps.