fix 404 page error issues in DNN site

I have a DNN site that we just established. I have installed Infinity URL Master on this site but it hasn't helped. We are getting error 404 page not found errors and need to correct it immediately for all of the old links that for obvious reasons no longer exist. I can provide ftp access as well as DNN host access. I suspect this is a very simple process for someone who knows what they're doing. Example: [login to view URL] should redirect to [login to view URL] total page redirects is less than 20.