You can find the instruction on How to set the home page.

If Google is set as your Homepage in Firefox you can middle-click (push down on the mouse wheel) to open Google in a new Tab.

Or, you can add the feature to Firefox where clicking the New Tab button on the Tab Bar opens your Homepage in a new Tab.
https://addons.mozilla.org/en-US/firefox/addon/new-tab-homepage/

And if you have a different Homepage set, this extension allows for any page you set in the extension's options to open when you use the new Tab button.
https://addons.mozilla.org/en-US/firefox/addon/newtaburl/

To set blank page as new tab you can alter config file by following intructions, near bottom of page in the link below.

http://support.mozilla.org/en-US/kb/new-tab-page-show-hide-and-customize-top-sites#w_how-do-i-turn-the-new-tab-page-off

If you want home page, follow the same instruction but type about:home instead of about:blank

Summary of steps shown below.

In the Location bar, type about:config and press ENTER

The about:config "This might void your warranty!" warning page may appear. Click I'll be careful, I promise!, to continue to the about:config page

Type browser.newtab.url in the search box.

Double-click the browser.newtab.url preference and change the url from about:newtab to about:blank (OR about:home if you require this).

Click OK and close the about:config tab.