I have a new computer with windows7 home premium, and use Firefox. My e-mil page is only half the width of the header with a very small font. How do I expand the page to full width and increase the size of the font? I would be grate ful for any help.

I assume you are referring to a webmail account such as gmail or hotmail.
Simply increase the font size in ff.
Either zoom in or make the change in options, content tab.