Well, you have a couple options.
First you have to decide which login you should use. I have several sites where I use the WWF login as the login for the entire website. You can also go the other way around and use something else to manage the login and have WWF use that. Borg built an API for that.
Search for site integration, a number of people, including myself, have written on the topic.
On non-forum pages, you basically have to include common.asp and then you have access to most of the forum variables, including who is logged in and what group then belong to. You then use if then statements to determine who can see things on the pages. For example, if the user is a guest, you can prevent them from seeing the content and instead ask them to login.
But do a search, this is easy to do. You don't have to worry about generating passwords or salt or anything. Just have WWF handle the logins and registrations.