When you are sure you have the password, you put it in the URL,like this: http://neutralriddle.50webs.com/folder/answer.htm
In others, you'll need external programs, such as Photoshop (download 30 day trial here), or The Gimp (Can be downloaded for free here), when it's about manipulating pictures. To manipulate Audio Files, i suggest the use of Audacity
That's what the forums are for, to guide you throughout the riddle.