Safari doesn't open PHP files

If i try to open a PHP file in safari, it shows the code. If the PHP file isn't local, for example, on a local website (using air sharing on my ipod touch and adding php files to it), it will download the file. If I open it there, it will only display the codes like it does on the original file on my mac. I'm trying to use wordpress but it doesn't work. Once I think i saw some of the page working (it was the login page and it was PHP). But i've tried everything i could do but it never worked again. Please help me! Thanks!