wp-admin/install.php does not do anything.

I have installed MAMP, and the system requirements have been verified.

I download wp 4.5 expand it and try to follow the 5 minute install, but all that happens when I try to launch install.php is that it opens up in textwrangler…
Tried editing the sample config and saving as wp-config.php, but the same thing happens…
I know my limitations and am not very versed in this, but I think I followed the instructions properly…
Any help would be appreciated as I have been at it for hours…
I even created a new user with admin rights and tried to install under the new account, but no luck.