Well , to learn PHP you need PHP on your PC . which is available at
www.php.net . but i would also recommend you to go for
XAMPP
Go to XAMPP
site and download XAMPP`s
.exe file which will be about 22 MB for complete version.
now install from the .exe file , by this you have
php(script language) ,
MySQL(database) and
Apache(server) installed on your PC .
now whenever you are learning or coding PHP just go to XAMPP control panel from startup menu and start PHP .
now for PHP designer , as common softwares, download & install it from their
website
In PHP designer to run PHP with along with PHPdesigner. (i.e for checking scripts u made)
put all your script files to
C:\apachefriends\xampp\htdocs (or wherever you installed XAMPP)
now the location
htdocs in your PC is
http://localhost/ in your browser i.e you can view a php script running in browser (PHP is a server side script) .
for e.g you saved a file named
index.php in C:\apachefriends\xampp\htdocs\
meme then in your browser it`s location is
http://localhost/meme
Try
googling for more tutorials on PHP