Ok, I will want to turn my computer into a server if possible, but how do I do it?

I am a linux noob at the moment and know nothing, can someone please help me? x.x
Turning it into a server is easy as cake.

Just simply download a Ubuntu live-CD (the text mode one!)
and hit "install server"

Now mind you, there will be NO GUI! You'll have to do everything by console (you can get a gui, but there's really no need to) so be prepared to read up on Linux terminal commands.
In response to Flame Sage
No no. If you're a linux noob, you still want to install a graphical operating system so that you can use the newbie-friendly graphical tools. This can be Windows or Linux, though obviously you're interested in linux since you asked here.

I suggest Ubuntu, since it is very newbie-friendly and is very easy to set up as many types of servers, including web server, FTP server, BYOND server, etc.

To install Ubuntu, just download the Desktop CD (or get one free through the mail! Click the "Get Ubuntu" link for instructions), put it in your CD drive, make sure your BIOS allows you to boot from a CD before hard drive (look for the BIOS setup key when your computer boots up... it's probably ESC or F6 or something), and then double-click the Install icon on your Ubuntu desktop.
In response to PirateHead
If you really want a good server OS, use Ubuntu's base, Debian. Both of my HyperBYOND servers run that.