Did you read the installation help/readme that comes with PHP?
Take a look at that, and look for a section specifically devoted to installing PHP in IIS. (I used the ISAPI .dll filter, up to you to decide how to install it)
If you STILL can't get it after reading that (please make your best effort - we're all about learning here, not spoonfeeding), let me know what you've done and I'll try to guide you from there.