There are three key ways in which you can generate content for your website.
The first way in which you can generate content for your website would be by researching, and then creating the content by yourself. If, for instance, you are thinking of developing a site offering people email account help for www.gmail.com, you can start by conducting research to understand the Gmail-related questions that people normally have. You can then go ahead to create content answering those questions, and ensure that such content is what populates your website.
The second way in which you can generate content for your website would be by hiring people to create the content for you.
And the third way in which you can generate content for your website would be by designing the site in such a manner that it can be populated with user-generated content. If, going by the example we looked at earlier, you want to create a site offering Gmail email account help, you can simply put in place a forum script. That would enable people to ask Gmail-related questions, and to have others on the site answer those questions. You can also use a blog script, like the one behind this post (in one of the popular Gmail help sites).