Since you are new with all this craziness, a little more info to help...
The site link that Peerless so wisely gave you is to a place where you can (and should !) download the 'Nimo Codecs Pack'...
CODEC simply means
COder /
DECoder - As MODEM means
MOdulator /
DEModulator ! OK ?
When you click on the link Peerless gave you, just select 'Download' and then
Build 8
from any of the 'sites' named with the word
available in the line.
Choose to SAVE (NOT Open) the file and after you have downloaded it, click on the new file and follow the install instructions... It is very simple and will make it possible for you to play almost any video or music file known to man !!!
The only thing you need to pay any attention to is regarding 2 files/CODECS that you almost certainly do NOT want to be installed... But, all of this is very clearly explained.
btw... It's ALL free
(All of the above is for Windows users only.)