Don't use the JavaScript redirect. It is a kiss of death with Google ever since it started reading JavaScript in the summer of 2004. Search engines that do not read JavaScript (almost all) will not be redirected to the new pages and the old page will stay in their database.
A JavaScript redirect was being used by a Las Vegas
SEO black hatter as a cloaking method that was redirecting users to another page. All of the
SEO company's clients were banned in July of 2004. Ever since then, a JavaScript redirect has been risky.
Are all the pages PHP pages? If so, there is a simple 301 redirect that can be added. I know you said that you don't know PHP, but this is a snippet of code that can be added to the top of the old PHP pages that redirects the old page to the new page. A 301 redirect tells the search engine to change the URL in their database.
Other than a 301 redirect, the best thing to do is to remove the old pages and let the spiders hit the 404 error. They will then remove the old URLs from their data. Make sure that you have a properly implemented error 404 page for any human visitors that find an obsolete URL.