Welcome to TG Colin,

I think the point to realize is that Web Designer is not a HTML editor, therefore it stands that it is not going to offer the same HTML layout tools as a traditional HTML editor.
With Web Designer there is NO HTML at all involved. You simply create your page design directly and graphically then 'export' the design to html.
Web Designers .web format is your design project file (always save a copy) which is 100% HTML free.

You can add HTML tables via a placeholder, but the <table> code will need to be created in a HTML editor (or notepad if you know how to code a table) first.

Same thing for framsets, these are HTML elements.
See here for a way to create something that works like a frameset in Web Designer.