/var/www/html/so you can uncompress the software there, but you can do it where you want if you take care to allow Apache to access that location. Now you have a directory called
/var/www/html/phpMyCatalogor something similar.
chmod 777[phpMyCatalog installation dir]
to achieve it.
initialize.sql should have the same permissions:
chmod 777 [phpMyCatalog installation dir]/initialize.sql
You can change permissions for directory and files as well with your fauvorite file manager.