Hi,
if you compiled php yourself the php.ini might not exist. The best way to solve that problem is to create a little php script that just contains
phpinf();
That will among many other things print the location where php searches for the php.ini file. You can then copy the php.ini-dist that comes with the source distribution of php to that location and rename it to php.ini. Then edit it to your needs 🙂
Thomas