Do not use frames for creating new pages. Older browsers don't recognise them and they can be hard to control. Make a mistake and the effect can be quite startling. They can be inaccessible to screen reader users. Also, Google won't index your site if it is built with frames.
If you really must use them, make sure each frame has a name that describes the frames content and use the <NOFRAMES> tag to provide a description of the content for users who cannot access them. Provided you do this your site will be legal, but not especially usable.
<FRAMESET title="Web page about....">
<FRAME src="menu.htm" title="Main menu">
<FRAME src="page.htm" title="Page content about...">
This is a description of the web site....
In theory, if you can give the user the link to the main menu, they should manage a degree of navigation by clicking on main links and using the back button - very messy.
Better still - don't fix a bad job and rebuild your website from scratch.