can't read index.php

[tintinak]

Hi, i use xampp 1.7.3 on lion os.
I have a big problem.
I put my website folder in htdocs, i run xampp (apache, mysql, ftp), but when i go to "localhost/mywebsite/index.php" my navigator (firefox or chrome) doesn't open the website but download the folder index.php
Somebody can help me?

PS: sorry for my english...