Some gestures have been removed in Firefox 4.
You can restore the zoom feature by changing the values of the related prefs on the about:config page.

browser.gesture.pinch.in cmd_fullZoomReduce
browser.gesture.pinch.in.shift cmd_fullZoomReset
browser.gesture.pinch.out cmd_fullZoomEnlarge
browser.gesture.pinch.out.shift cmd_fullZoomReset

• http://kb.mozillazine.org/about%3Aconfig

I don't know what I'm looking at.

Sorry I'm not a big computer guy.

I guess I'll see if Chrome lets me use this function. :-(

You can type about:config in the location bar and press the Enter key to open the about:config page. That is a special page that show all preferences of Firefox in a long list. You can accept the warning that you will be careful.

If you type [b]gesture/b in the Filter bar that shows at the top of that page then you get a list of the browser.gesture prefs. You can double click each of the browser.gesture.pinch. prefs and change their values from an empty string to the indicated value.
You can read more about the about:config in this mozillaZine Knowledge Base article:

• http://kb.mozillazine.org/about%3Aconfig

browser.gesture.pinch.in -> cmd_fullZoomReduce
browser.gesture.pinch.in.shift -> cmd_fullZoomReset
browser.gesture.pinch.out -> cmd_fullZoomEnlarge
browser.gesture.pinch.out.shift -> cmd_fullZoomReset