I installed phpstorm so I can learn PHP.
Because phpstorm could not find PHP I installed easyphp.
But I cannot point phpstorm so I will use the php installed by easyphp.
Edit 1: I forget to say I work on a Windows 7 computer
Your are on Windows. Now find your php.exe. Lets assume that it is in C:\PHP\php.exe.
In PhpStorm you need provide path to that folder, which is C:\PHP (based on our example)
If PhpStorm is still unable to recognize it -- maybe you have problem in your php.ini. I suggest run it in command line and see if it will produce any errors (e.g. php.exe -v or php.exe -i). You can always delete your php.ini and use one of the defaults suppried with php (e.g. php.ini-development -- rename to php.ini and configure as required).
Regarding EasyPHP. It can be installed in folder named something like this (depends how you installed it, of course): C:\EasyPHP-5.3.9\php\php539x130201222616\php.exe