I know I can view the source code copy that and paste it into a notepad doc. Then I can save that file and wolla I have the total size of the code.
But I have the webdeveloper toolbar plugin for Firefox. isnt there an easier way using this toolbar? If so where is it?
If you just want the size of the page you are on (as in the HTML file) to the equivalent of copy pasting into notepad, why not just right click “View Page Info” and look to “Size” which provides the file size of the document (excluding images or external resources). Simple and does what you were attempting. 
see i dont have that? weird…maybe i have an old version
Options > About
Web Developer 1.1.8 Build June 30, 2009
According to the developers site it’s the latest: http://chrispederick.com/work/web-developer/
Don’t you have the whole Tools section, or just this one option? Tools is actually just a bunch of links that use the current url as a querystring, just go to “Edit tools” and at this to it (Tool type URL):
Also, Firebug & YSlow are imho superior in helping you reduce page size and page speed, which is I assume you’re up to since this is in SEO. Do some Google searches for those and you should find some tutorials on this matter.
On the toolbar:
Tools > View Speed Report
I’d also recommend Firebug combined with YSlow.