After Installing APACHE, PHP, PERL & MySQL
 

I know nothing about APACHE, PHP, PERL & MySQL. But I wanna learn these Server Side Giants. I've installed them now what should I do & from where should I begin ???

It would be best to look at each of the offical websites. It would also be wise to buy books on the matters.

PHP and perl are langauges, asuming you know how to write in it the only thing you can do is configure /secure them to your needs, refer to php.net and perl's site.

MySQL i think is quite striaght forward (just install really)...
Apache will probabily need configuring /tweeking /securing but nothing too complex i presume. It also has a thing called .htaccess you might want to read up on.

You're not looking at a lot.
Apache is the server... MySQL is just a database and PHP /perl are scripting languages/interpreters... most of your time will probabily be spent learning to program in PHP /PHP&MySQL (and perl if you would even need a second scripting language alongside php?)

all of which can be searched on the internet..

Php.net has tutorials...
google php tutorials
google .htaccess tutorials
google configuring apache
google securing apache...
...