Hi sumella,
I think you should try an Add-on like one of these:
Tab Mix Plus
New Tab Button on tab bar

Thank you alco for the Add-ons. I remember doing something to Firefox script to duplicate the new tab button but I forgot :-(

Thanks!

You can drag the New Tab button from the Tab bar on another toolbar and use this code in userChrome.css to make both New Tab buttons visible.

Add code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css

The customization files userChrome.css (interface) and userContent.css (websites) are located in the chrome folder in the user profile folder.

• http://kb.mozillazine.org/Editing_configuration

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* show New Tab button on toolbar */
#new-tab-button { visibility: visible !important; }
/* show New Tab button on tab bar */
.tabs-newtab-button { visibility: visible !important; }

Hi Cor-el, perhaps I am doing something wrong :-( I tried the above but it doesn't seem to work for me. I had to create the chrome folder in my profile folder, and then add the userChrome.css file however. I dragged the tab button which is the + onto another toolbar, but the original does not show even after the css modification. Please help :-) Thanks.

Works for me with the default theme if there aren't a lot of tabs open (no scroll buttons).
If you use tab related extensions that maintain their own buttons then it may not work.
You should see two plus buttons on the tab bar if the code is working properly, one right after the last tab (that one may disappear if you open enough tabs to make scroll buttons appear) and a second plus right after the last tab.

Does other code in the userChrome.css file work?

Thank you cor-el. That was my bad. I forgot to change the extension to css as notepad creates .txt as a default. Thank you it works great! :-)