Step-By-Step Tutorial for fixing looping music/sound

Well I found some threads how to fix sound loops and make the longer than normal:
http://steamcommunity.com/app/218620/discussions/15/43099721383227159/
http://steamcommunity.com/app/218620/discussions/15/540744299835792525/
But I have no idea about them. What shouldI open? How should I edit it?
Can someone please make a step-by-step tutorial?
Replies
Okay, got the 3 results, and found the DATA section, but i leave it there. I have no idea about hex editing, and I don't understand the guide that much.
Is there maybe anouther way to edit the lenght and loop?