I don't understand your problem. Have you downloaded Firefox?
Firefox download
Just open both and they will show up in your Taskbar at the bottom.

When you download Firefox it should place a 'shortcut' on your desktop. You can either use the 'shortcut' from the desktop,drag the shortcut to your 'Quick Launch' in the taskbar like cboy recommended, or right click the shortcut and 'Pin to start menu'.
You can have IE and Firefox open at the same time and switch between the two from the taskbar.
Witz

Tks to both of you. I want to be able to make IE or Firefox my default browser. Is there a way to do that?

It should give you that choice during installation. If not open firefox and click tools > options > main and at the bottom of the dialog box you will see a place to check if you want firefox to check to see if it is the default browser at startup. To the right is a 'check now' button. If you click it you can make firefox default there.

To make 'Internet Explorer' the default browser go to 'Tools/Internet Options/Programs Tab- at the bootom check the box 'IE should check to see whether it is the default browser'.
That's if your using 'IE6', I haven't switched over to IE7 yet.
Witz

I got 'er done. Tks so much.

My husband and I use FireFox all the time, but for the rare occasions when some site won't work (a video, for instance) in FF, we just right-click and choose 'View this page in IE," so we don't have to have two browsers open all the time. This function I mentioned is thanks to the FF add-on called IE View.

There is a smaller add-on called IE View Lite, by another programmer, but that wouldn't work right for me, so I went back to the original IE View. I had a hard time finding the download for it, though. Using Search kept bringing up IE View Lite. The original is on p.3 or later of the results, so in case you need it, here is a link.

Here is a link that might be useful: The original IE View