[PHP] Question about php.ini and dynamic extensions

[Joelmon2001]

Hello, if I want to be able to load dynamic extensions via php, do I just go 
to
php.ini and under

;;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
 ;;;;;;;;;;;;;;;;;;;;;;

Do I just add the extensions I need?
   extension=msql.so
   extension=gd.so
   extension=xml.so

making sure they are uncommented ?

And then just save the file and reload apache?

In the php page, would
dl("gd.so");

activate it? Is this how to do it?

Thanks