When you click on a link that is on a webpage right click and click on "Open Link in new tab" this will open the new page in a new tab and keep your old tab open. If you want to open a new tab without clicking on a link on a web page click on the plus button near your currently open tab(s).

You can also middle-click the link (press the mouse wheel) to open a link or bookmark in a new tab.

You can install the Tabs Mix Plus add on.

On the links tab at the bottom is the choice to force all links to open in a new tab.

I like this because I can click links on the page I'm reading without losing the page... and can read the other links later in the new tabs.

It does have the downside that you wind up closing a lot of tabs, but it's a small price to pay.

I was unable to find the "Tabs Mix Plus" add on but I was able to open a new tab by right clicking on the web link first. I will continue to hunt for the Tabs Mix Plus add on and try that out when I find it. Thanks